Connection

class
Superclass
rb_cObject
Included Modules
PG::Constants

The PostgreSQL connection class. The interface for this class is based on libpq, the C application programmer’s interface to PostgreSQL. Some familiarity with libpq is recommended, but not necessary.

For example, to send query to the database on the localhost:

require 'pg'
conn = PG::Connection.open(:dbname => 'test')
res = conn.exec_params('SELECT $1 AS a, $2 AS b, $3 AS c', [1, 2, nil])
# Equivalent to:
#  res  = conn.exec('SELECT 1 AS a, 2 AS b, NULL AS c')

See the PG::Result class for information on working with the results of a query.

Many methods of this class have three variants kind of:

  1. exec - the base method which is an alias to async_exec . This is the method that should be used in general.

  2. async_exec - the async aware version of the method, implemented by libpq’s async API.

  3. sync_exec - the method version that is implemented by blocking function(s) of libpq.

Sync and async version of the method can be switched by Connection.async_api= , however it is not recommended to change the default.

Constants

CONNECT_ARGUMENT_ORDER

The order the options are passed to the ::connect method.

REDIRECT_CLASS_METHODS
REDIRECT_METHODS
REDIRECT_SEND_METHODS

These methods are affected by PQsetnonblocking

Public Class Methods

anchor
async_api=(enable)

Switch between sync and async libpq API.

PG::Connection.async_api = true

this is the default. It sets an alias from exec to async_exec, reset to async_reset and so on.

PG::Connection.async_api = false

sets an alias from exec to sync_exec, reset to sync_reset and so on.

pg-1.1.0+ defaults to libpq’s async API for query related blocking methods. pg-1.3.0+ defaults to libpq’s async API for all possibly blocking methods.

PLEASE NOTE: This method is not part of the public API and is for debug and development use only. Do not use this method in production code. Any issues with the default setting of async_api=true should be reported to the maintainers instead.

# File lib/pg/connection.rb, line 863
def async_api=(enable)
        self.async_send_api = enable
        REDIRECT_METHODS.each do |ali, (async, sync)|
                remove_method(ali) if method_defined?(ali)
                alias_method( ali, enable ? async : sync )
        end
        REDIRECT_CLASS_METHODS.each do |ali, (async, sync)|
                singleton_class.remove_method(ali) if method_defined?(ali)
                singleton_class.alias_method(ali, enable ? async : sync )
        end
end
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn
Alias for: new
anchor
PG::Connection.ping(connection_hash) → Integer
PG::Connection.ping(connection_string) → Integer
PG::Connection.ping(host, port, options, tty, dbname, login, password) → Integer
Alias for: ping
anchor
async_send_api=(enable)
# File lib/pg/connection.rb, line 840
def async_send_api=(enable)
        REDIRECT_SEND_METHODS.each do |ali, (async, sync)|
                undef_method(ali) if method_defined?(ali)
                alias_method( ali, enable ? async : sync )
        end
end
anchor
PG::Connection.conndefaults() → Array

Returns an array of hashes. Each hash has the keys:

:keyword

the name of the option

:envvar

the environment variable to fall back to

:compiled

the compiled in option as a secondary fallback

:val

the option’s current value, or nil if not known

:label

the label for the field

:dispchar

“” for normal, “D” for debug, and “*” for password

:dispsize

field size

static VALUE
pgconn_s_conndefaults(VALUE self)
{
        PQconninfoOption *options = PQconndefaults();
        VALUE array = pgconn_make_conninfo_array( options );

        PQconninfoFree(options);

        UNUSED( self );

        return array;
}
anchor
conndefaults_hash()

Return the Postgres connection defaults structure as a Hash keyed by option keyword (as a Symbol).

See also conndefaults

# File lib/pg/connection.rb, line 260
def self.conndefaults_hash
        return self.conndefaults.each_with_object({}) do |info, hash|
                hash[ info[:keyword].to_sym ] = info[:val]
        end
end
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn
Alias for: new
anchor
connect_hash_to_string( hash )

Convert Hash options to connection String

Values are properly quoted and escaped.

# File lib/pg/connection.rb, line 44
def self.connect_hash_to_string( hash )
        hash.map { |k,v| "#{k}=#{quote_connstr(v)}" }.join( ' ' )
end
anchor
PG::Connection.connect_start(connection_hash) → conn
PG::Connection.connect_start(connection_string) → conn
PG::Connection.connect_start(host, port, options, tty, dbname, login, password) → conn

This is an asynchronous version of PG::Connection.new.

Use connect_poll to poll the status of the connection.

NOTE: this does not set the connection’s client_encoding for you if Encoding.default_internal is set. To set it after the connection is established, call internal_encoding=. You can also set it automatically by setting ENV['PGCLIENTENCODING'], or include the ‘options’ connection parameter.

See also the ‘sample’ directory of this gem and the corresponding libpq functions.

static VALUE
pgconn_s_connect_start( int argc, VALUE *argv, VALUE klass )
{
        VALUE rb_conn;
        VALUE conninfo;
        t_pg_connection *this;

        /*
         * PG::Connection.connect_start must act as both alloc() and initialize()
         * because it is not invoked by calling new().
         */
        rb_conn  = pgconn_s_allocate( klass );
        this = pg_get_connection( rb_conn );
        conninfo = rb_funcall2( klass, rb_intern("parse_connect_args"), argc, argv );
        this->pgconn = gvl_PQconnectStart( StringValueCStr(conninfo) );

        if( this->pgconn == NULL )
                rb_raise(rb_ePGerror, "PQconnectStart() unable to allocate PGconn structure");

        if ( PQstatus(this->pgconn) == CONNECTION_BAD )
                pg_raise_conn_error( rb_eConnectionBad, rb_conn, "%s", PQerrorMessage(this->pgconn));

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_conn, pgconn_finish, rb_conn );
        }
        return rb_conn;
}
anchor
PG::Connection.conninfo_parse(conninfo_string) → Array

Returns parsed connection options from the provided connection string as an array of hashes. Each hash has the same keys as PG::Connection.conndefaults() . The values from the conninfo_string are stored in the :val key.

static VALUE
pgconn_s_conninfo_parse(VALUE self, VALUE conninfo)
{
        VALUE array;
        char *errmsg = NULL;
        PQconninfoOption *options = PQconninfoParse(StringValueCStr(conninfo), &errmsg);
        if(errmsg){
                VALUE error = rb_str_new_cstr(errmsg);
                PQfreemem(errmsg);
                rb_raise(rb_ePGerror, "%"PRIsVALUE, error);
        }
        array = pgconn_make_conninfo_array( options );

        PQconninfoFree(options);

        UNUSED( self );

        return array;
}
anchor
PG::Connection.encrypt_password( password, username ) → String

This is an older, deprecated version of encrypt_password. The difference is that this function always uses md5 as the encryption algorithm.

static VALUE
pgconn_s_encrypt_password(VALUE self, VALUE password, VALUE username)
{
        char *encrypted = NULL;
        VALUE rval = Qnil;

        UNUSED( self );

        Check_Type(password, T_STRING);
        Check_Type(username, T_STRING);

        encrypted = PQencryptPassword(StringValueCStr(password), StringValueCStr(username));
        rval = rb_str_new2( encrypted );
        PQfreemem( encrypted );

        return rval;
}
anchor
escape_bytea( string ) → String

Escapes binary data for use within an SQL command with the type bytea.

Certain byte values must be escaped (but all byte values may be escaped) when used as part of a bytea literal in an SQL statement. In general, to escape a byte, it is converted into the three digit octal number equal to the octet value, and preceded by two backslashes. The single quote (‘) and backslash () characters have special alternative escape sequences. escape_bytea performs this operation, escaping only the minimally required bytes.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

static VALUE
pgconn_s_escape_bytea(VALUE self, VALUE str)
{
        unsigned char *from, *to;
        size_t from_len, to_len;
        VALUE ret;

        Check_Type(str, T_STRING);
        from      = (unsigned char*)RSTRING_PTR(str);
        from_len  = RSTRING_LEN(str);

        if ( rb_obj_is_kind_of(self, rb_cPGconn) ) {
                to = PQescapeByteaConn(pg_get_pgconn(self), from, from_len, &to_len);
        } else {
                to = PQescapeBytea( from, from_len, &to_len);
        }

        ret = rb_str_new((char*)to, to_len - 1);
        PQfreemem(to);
        return ret;
}
anchor
escape_string( str ) → String

Returns a SQL-safe version of the String str. This is the preferred way to make strings safe for inclusion in SQL queries.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

Character encoding of escaped string will be equal to client encoding of connection.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

See also convenience functions escape_literal and escape_identifier which also add proper quotes around the string.

static VALUE
pgconn_s_escape(VALUE self, VALUE string)
{
        size_t size;
        int error;
        VALUE result;
        int enc_idx;
        int singleton = !rb_obj_is_kind_of(self, rb_cPGconn);

        StringValueCStr(string);
        enc_idx = singleton ? ENCODING_GET(string) : pg_get_connection(self)->enc_idx;
        if( ENCODING_GET(string) != enc_idx ){
                string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
        }

        result = rb_str_new(NULL, RSTRING_LEN(string) * 2 + 1);
        PG_ENCODING_SET_NOCHECK(result, enc_idx);
        if( !singleton ) {
                size = PQescapeStringConn(pg_get_pgconn(self), RSTRING_PTR(result),
                        RSTRING_PTR(string), RSTRING_LEN(string), &error);
                if(error)
                        pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(pg_get_pgconn(self)));

        } else {
                size = PQescapeString(RSTRING_PTR(result), RSTRING_PTR(string), RSTRING_LEN(string));
        }
        rb_str_set_len(result, size);

        return result;
}
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn

Create a connection to the specified server.

connection_hash must be a ruby Hash with connection parameters. See the list of valid parameters in the PostgreSQL documentation.

There are two accepted formats for connection_string: plain keyword = value strings and URIs. See the documentation of connection strings.

The positional parameter form has the same functionality except that the missing parameters will always take on default values. The parameters are:

host

server hostname

port

server port number

options

backend options

tty

(ignored in all versions of PostgreSQL)

dbname

connecting database name

user

login user name

password

login password

Examples:

# Connect using all defaults
PG::Connection.new

# As a Hash
PG::Connection.new( dbname: 'test', port: 5432 )

# As a String
PG::Connection.new( "dbname=test port=5432" )

# As an Array
PG::Connection.new( nil, 5432, nil, nil, 'test', nil, nil )

# As an URI
PG::Connection.new( "postgresql://user:pass@pgsql.example.com:5432/testdb?sslmode=require" )

If the Ruby default internal encoding is set (i.e., Encoding.default_internal != nil), the connection will have its client_encoding set accordingly.

Raises a PG::Error if the connection fails.

# File lib/pg/connection.rb, line 659
def new(*args, **kwargs)
        conn = connect_to_hosts(*args, **kwargs)

        if block_given?
                begin
                        return yield conn
                ensure
                        conn.finish
                end
        end
        conn
end
Also aliased as: async_connect , connect , open , setdb , setdblogin
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn
Alias for: new
anchor
parse_connect_args( *args )

Parse the connection args into a connection-parameter string. See PG::Connection.new for valid arguments.

It accepts:

  • an option String kind of “host=name port=5432”

  • an option Hash kind of {host: “name”, port: 5432}

  • URI string

  • URI object

  • positional arguments

The method adds the option “fallback_application_name” if it isn’t already set. It returns a connection string with “key=value” pairs.

# File lib/pg/connection.rb, line 60
def self.parse_connect_args( *args )
        hash_arg = args.last.is_a?( Hash ) ? args.pop.transform_keys(&:to_sym) : {}
        iopts = {}

        if args.length == 1
                case args.first
                when URI, /=/, /:\/\//
                        # Option or URL string style
                        conn_string = args.first.to_s
                        iopts = PG::Connection.conninfo_parse(conn_string).each_with_object({}){|h, o| o[h[:keyword].to_sym] = h[:val] if h[:val] }
                else
                        # Positional parameters (only host given)
                        iopts[CONNECT_ARGUMENT_ORDER.first.to_sym] = args.first
                end
        else
                # Positional parameters with host and more
                max = CONNECT_ARGUMENT_ORDER.length
                raise ArgumentError,
                                "Extra positional parameter %d: %p" % [ max + 1, args[max] ] if args.length > max

                CONNECT_ARGUMENT_ORDER.zip( args ) do |(k,v)|
                        iopts[ k.to_sym ] = v if v
                end
                iopts.delete(:tty) # ignore obsolete tty parameter
        end

        iopts.merge!( hash_arg )

        if !iopts[:fallback_application_name]
                iopts[:fallback_application_name] = $0.sub( /^(.{30}).{4,}(.{30})$/ ){ $1+"..."+$2 }
        end

        return connect_hash_to_string(iopts)
end
anchor
PG::Connection.ping(connection_hash) → Integer
PG::Connection.ping(connection_string) → Integer
PG::Connection.ping(host, port, options, tty, dbname, login, password) → Integer

Check server status.

See PG::Connection.new for a description of the parameters.

Returns one of:

PQPING_OK

server is accepting connections

PQPING_REJECT

server is alive but rejecting connections

PQPING_NO_RESPONSE

could not establish connection

PQPING_NO_ATTEMPT

connection not attempted (bad params)

# File lib/pg/connection.rb, line 788
def ping(*args)
        if Fiber.respond_to?(:scheduler) && Fiber.scheduler
                # Run PQping in a second thread to avoid blocking of the scheduler.
                # Unfortunately there's no nonblocking way to run ping.
                Thread.new { sync_ping(*args) }.value
        else
                sync_ping(*args)
        end
end
Also aliased as: async_ping
anchor
quote_connstr( value )

Quote a single value for use in a connection-parameter string.

# File lib/pg/connection.rb, line 37
def self.quote_connstr( value )
        return "'" + value.to_s.gsub( /[\\']/ ) {|m| '\\' + m } + "'"
end
anchor
quote_ident( str ) → String
quote_ident( array ) → String
PG::Connection.quote_ident( str ) → String
PG::Connection.quote_ident( array ) → String

Returns a string that is safe for inclusion in a SQL query as an identifier. Note: this is not a quote function for values, but for identifiers.

For example, in a typical SQL query: SELECT FOO FROM MYTABLE The identifier FOO is folded to lower case, so it actually means foo. If you really want to access the case-sensitive field name FOO, use this function like conn.quote_ident('FOO'), which will return "FOO" (with double-quotes). PostgreSQL will see the double-quotes, and it will not fold to lower case.

Similarly, this function also protects against special characters, and other things that might allow SQL injection if the identifier comes from an untrusted source.

If the parameter is an Array, then all it’s values are separately quoted and then joined by a “.” character. This can be used for identifiers in the form “schema”.“table”.“column” .

This method is functional identical to the encoder PG::TextEncoder::Identifier .

If the instance method form is used and the input string character encoding is different to the connection encoding, then the string is converted to this encoding, so that the returned string is always encoded as PG::Connection#internal_encoding .

In the singleton form (PG::Connection.quote_ident) the character encoding of the result string is set to the character encoding of the input string.

static VALUE
pgconn_s_quote_ident(VALUE self, VALUE str_or_array)
{
        VALUE ret;
        int enc_idx;

        if( rb_obj_is_kind_of(self, rb_cPGconn) ){
                enc_idx = pg_get_connection(self)->enc_idx;
        }else{
                enc_idx = RB_TYPE_P(str_or_array, T_STRING) ? ENCODING_GET( str_or_array ) : rb_ascii8bit_encindex();
        }
        pg_text_enc_identifier(NULL, str_or_array, NULL, &ret, enc_idx);

        return ret;
}
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn
Alias for: new
anchor
PG::Connection.new → conn
PG::Connection.new(connection_hash) → conn
PG::Connection.new(connection_string) → conn
PG::Connection.new(host, port, options, tty, dbname, user, password) → conn
Alias for: new
anchor
sync_connect(*args)
static VALUE
pgconn_s_sync_connect(int argc, VALUE *argv, VALUE klass)
{
        t_pg_connection *this;
        VALUE conninfo;
        VALUE self = pgconn_s_allocate( klass );

        this = pg_get_connection( self );
        conninfo = rb_funcall2( rb_cPGconn, rb_intern("parse_connect_args"), argc, argv );
        this->pgconn = gvl_PQconnectdb(StringValueCStr(conninfo));

        if(this->pgconn == NULL)
                rb_raise(rb_ePGerror, "PQconnectdb() unable to allocate PGconn structure");

        if (PQstatus(this->pgconn) == CONNECTION_BAD)
                pg_raise_conn_error( rb_eConnectionBad, self, "%s", PQerrorMessage(this->pgconn));

        pgconn_set_default_encoding( self );

        if (rb_block_given_p()) {
                return rb_ensure(rb_yield, self, pgconn_finish, self);
        }
        return self;
}
anchor
sync_ping(*args)
static VALUE
pgconn_s_sync_ping( int argc, VALUE *argv, VALUE klass )
{
        PGPing ping;
        VALUE conninfo;

        conninfo = rb_funcall2( klass, rb_intern("parse_connect_args"), argc, argv );
        ping     = gvl_PQping( StringValueCStr(conninfo) );

        return INT2FIX((int)ping);
}
anchor
PG::Connection.unescape_bytea( string )

Converts an escaped string representation of binary data into binary data — the reverse of escape_bytea. This is needed when retrieving bytea data in text format, but not when retrieving it in binary format.

static VALUE
pgconn_s_unescape_bytea(VALUE self, VALUE str)
{
        unsigned char *from, *to;
        size_t to_len;
        VALUE ret;

        UNUSED( self );

        Check_Type(str, T_STRING);
        from = (unsigned char*)StringValueCStr(str);

        to = PQunescapeBytea(from, &to_len);

        ret = rb_str_new((char*)to, to_len);
        PQfreemem(to);
        return ret;
}

Public Instance Methods

anchor
async_cancel()
Alias for: cancel
anchor
async_describe_portal(p1)

Retrieve information about the portal portal_name.

See also corresponding libpq function.

Alias for: describe_portal
anchor
async_describe_prepared(p1)

Retrieve information about the prepared statement statement_name.

See also corresponding libpq function.

Alias for: describe_prepared
anchor
async_encrypt_password( password, username, algorithm=nil )
Alias for: encrypt_password
anchor
async_exec(*args)

Sends SQL query request specified by sql to PostgreSQL. On success, it returns a PG::Result instance with all result rows and columns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call exec_params for you. New code should explicitly use exec_params if argument placeholders are used.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

exec is an alias for async_exec which is almost identical to sync_exec . sync_exec is implemented on the simpler synchronous command processing API of libpq, whereas async_exec is implemented on the asynchronous API and on ruby’s IO mechanisms. Only async_exec is compatible to Fiber.scheduler based asynchronous IO processing introduced in ruby-3.0. Both methods ensure that other threads can process while waiting for the server to complete the request, but sync_exec blocks all signals to be processed until the query is finished. This is most notably visible by a delayed reaction to Control+C. It’s not recommended to use explicit sync or async variants but exec instead, unless you have a good reason to do so.

See also corresponding libpq function.

Also aliased as: async_query
Alias for: exec
anchor
async_exec_params(*args)

Sends SQL query request specified by sql to PostgreSQL using placeholders for parameters.

Returns a PG::Result instance on success. On failure, it raises a PG::Error.

params is an array of the bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :type   => Integer (oid of type of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :type => 0, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

The primary advantage of exec_params over exec is that parameter values can be separated from the command string, thus avoiding the need for tedious and error-prone quoting and escaping. Unlike exec, exec_params allows at most one SQL command in the given string. (There can be semicolons in it, but not more than one nonempty command.) This is a limitation of the underlying protocol, but has some usefulness as an extra defense against SQL-injection attacks.

See also corresponding libpq function.

Alias for: exec_params
anchor
async_exec_prepared(*args)

Execute prepared named statement specified by statement_name. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

params is an array of the optional bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec_prepared returns the value of the block.

See also corresponding libpq function.

Alias for: exec_prepared
anchor
async_flush()

Attempts to flush any queued output data to the server. Returns true if data is successfully flushed, false if not. It can only return false if connection is in nonblocking mode. Raises PG::Error if some other failure occurred.

Alias for: flush
anchor
async_get_copy_data(async=false, decoder=nil)
Alias for: get_copy_data
anchor
async_get_last_result()

This function retrieves all available results on the current connection (from previously issued asynchronous commands like +send_query()+) and returns the last non-NULL result, or nil if no results are available.

If the last result contains a bad result_status, an appropriate exception is raised.

This function is similar to get_result except that it is designed to get one and only one result and that it checks the result state.

Alias for: get_last_result
anchor
async_get_result()
Alias for: get_result
anchor
async_isnonblocking()
Alias for: isnonblocking
anchor
async_prepare(*args)

Prepares statement sql with name name to be executed later. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

param_types is an optional parameter to specify the Oids of the types of the parameters.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query.

See also corresponding libpq function.

Alias for: prepare
anchor
async_put_copy_data(buffer, encoder=nil)
Alias for: put_copy_data
anchor
async_put_copy_end(*args)
Alias for: put_copy_end
anchor
async_query(*args)

Sends SQL query request specified by sql to PostgreSQL. On success, it returns a PG::Result instance with all result rows and columns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call exec_params for you. New code should explicitly use exec_params if argument placeholders are used.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

exec is an alias for async_exec which is almost identical to sync_exec . sync_exec is implemented on the simpler synchronous command processing API of libpq, whereas async_exec is implemented on the asynchronous API and on ruby’s IO mechanisms. Only async_exec is compatible to Fiber.scheduler based asynchronous IO processing introduced in ruby-3.0. Both methods ensure that other threads can process while waiting for the server to complete the request, but sync_exec blocks all signals to be processed until the query is finished. This is most notably visible by a delayed reaction to Control+C. It’s not recommended to use explicit sync or async variants but exec instead, unless you have a good reason to do so.

See also corresponding libpq function.

Alias for: async_exec
anchor
async_reset()
Alias for: reset
anchor
async_set_client_encoding(p1)

Sets the client encoding to the encoding String.

Alias for: set_client_encoding
anchor
async_setnonblocking(enabled)
Alias for: setnonblocking
anchor
backend_key() → Integer

Returns the key of the backend server process for this connection. This key can be used to cancel queries on the server.

static VALUE
pgconn_backend_key(VALUE self)
{
        int be_key;
        struct pg_cancel *cancel;
        PGconn *conn = pg_get_pgconn(self);

        cancel = (struct pg_cancel*)PQgetCancel(conn);
        if(cancel == NULL)
                pg_raise_conn_error( rb_ePGerror, self, "Invalid connection!");

        if( cancel->be_pid != PQbackendPID(conn) )
                rb_raise(rb_ePGerror,"Unexpected binary struct layout - please file a bug report at ruby-pg!");

        be_key = cancel->be_key;

        PQfreeCancel(cancel);

        return INT2NUM(be_key);
}
anchor
backend_pid() → Integer

Returns the process ID of the backend server process for this connection. Note that this is a PID on database server host.

static VALUE
pgconn_backend_pid(VALUE self)
{
        return INT2NUM(PQbackendPID(pg_get_pgconn(self)));
}
anchor
block( [ timeout ] ) → Boolean

Blocks until the server is no longer busy, or until the optional timeout is reached, whichever comes first. timeout is measured in seconds and can be fractional.

Returns false if timeout is reached, true otherwise.

If true is returned, conn.is_busy will return false and conn.get_result will not block.

VALUE
pgconn_block( int argc, VALUE *argv, VALUE self ) {
        struct timeval timeout;
        struct timeval *ptimeout = NULL;
        VALUE timeout_in;
        double timeout_sec;
        void *ret;

        if ( rb_scan_args(argc, argv, "01", &timeout_in) == 1 ) {
                timeout_sec = NUM2DBL( timeout_in );
                timeout.tv_sec = (time_t)timeout_sec;
                timeout.tv_usec = (suseconds_t)((timeout_sec - (long)timeout_sec) * 1e6);
                ptimeout = &timeout;
        }

        ret = wait_socket_readable( self, ptimeout, get_result_readable);

        if( !ret )
                return Qfalse;

        return Qtrue;
}
anchor
cancel() → String

Requests cancellation of the command currently being processed.

Returns nil on success, or a string containing the error message if a failure occurs.

# File lib/pg/connection.rb, line 485
def cancel
        be_pid = backend_pid
        be_key = backend_key
        cancel_request = [0x10, 1234, 5678, be_pid, be_key].pack("NnnNN")

        if Fiber.respond_to?(:scheduler) && Fiber.scheduler && RUBY_PLATFORM =~ /mingw|mswin/
                # Ruby's nonblocking IO is not really supported on Windows.
                # We work around by using threads and explicit calls to wait_readable/wait_writable.
                cl = Thread.new(socket_io.remote_address) { |ra| ra.connect }.value
                begin
                        cl.write_nonblock(cancel_request)
                rescue IO::WaitReadable, Errno::EINTR
                        cl.wait_writable
                        retry
                end
                begin
                        cl.read_nonblock(1)
                rescue IO::WaitReadable, Errno::EINTR
                        cl.wait_readable
                        retry
                rescue EOFError
                end
        elsif RUBY_ENGINE == 'truffleruby'
                begin
                        cl = socket_io.remote_address.connect
                rescue NotImplementedError
                        # Workaround for truffleruby < 21.3.0
                        cl2 = Socket.for_fd(socket_io.fileno)
                        cl2.autoclose = false
                        adr = cl2.remote_address
                        if adr.ip?
                                cl = TCPSocket.new(adr.ip_address, adr.ip_port)
                                cl.autoclose = false
                        else
                                cl = UNIXSocket.new(adr.unix_path)
                                cl.autoclose = false
                        end
                end
                cl.write(cancel_request)
                cl.read(1)
        else
                cl = socket_io.remote_address.connect
                # Send CANCEL_REQUEST_CODE and parameters
                cl.write(cancel_request)
                # Wait for the postmaster to close the connection, which indicates that it's processed the request.
                cl.read(1)
        end

        cl.close
        nil
rescue SystemCallError => err
        err.to_s
end
Also aliased as: async_cancel
anchor
client_encoding=(p1)

Sets the client encoding to the encoding String.

Alias for: set_client_encoding
anchor
close()

Closes the backend connection.

Alias for: finish
anchor
conndefaults()

Returns an array of Hashes with connection defaults. See ::conndefaults for details.

# File lib/pg/connection.rb, line 252
def conndefaults
        return self.class.conndefaults
end
anchor
conndefaults_hash()

Returns a Hash with connection defaults. See ::conndefaults_hash for details.

# File lib/pg/connection.rb, line 268
def conndefaults_hash
        return self.class.conndefaults_hash
end
anchor
connect_poll() → Integer

Returns one of:

PGRES_POLLING_READING

wait until the socket is ready to read

PGRES_POLLING_WRITING

wait until the socket is ready to write

PGRES_POLLING_FAILED

the asynchronous connection has failed

PGRES_POLLING_OK

the asynchronous connection is ready

Example:

require "io/wait"

conn = PG::Connection.connect_start(dbname: 'mydatabase')
status = conn.connect_poll
while(status != PG::PGRES_POLLING_OK) do
  # do some work while waiting for the connection to complete
  if(status == PG::PGRES_POLLING_READING)
    unless conn.socket_io.wait_readable(10.0)
      raise "Asynchronous connection timed out!"
    end
  elsif(status == PG::PGRES_POLLING_WRITING)
    unless conn.socket_io.wait_writable(10.0)
      raise "Asynchronous connection timed out!"
    end
  end
  status = conn.connect_poll
end
# now conn.status == CONNECTION_OK, and connection
# is ready.
static VALUE
pgconn_connect_poll(VALUE self)
{
        PostgresPollingStatusType status;
        status = gvl_PQconnectPoll(pg_get_pgconn(self));

        pgconn_close_socket_io(self);

        return INT2FIX((int)status);
}
anchor
connection_needs_password() → Boolean

Returns true if the authentication method required a password, but none was available. false otherwise.

static VALUE
pgconn_connection_needs_password(VALUE self)
{
        return PQconnectionNeedsPassword(pg_get_pgconn(self)) ? Qtrue : Qfalse;
}
anchor
connection_used_password() → Boolean

Returns true if the authentication method used a caller-supplied password, false otherwise.

static VALUE
pgconn_connection_used_password(VALUE self)
{
        return PQconnectionUsedPassword(pg_get_pgconn(self)) ? Qtrue : Qfalse;
}
anchor
conninfo → hash

Returns the connection options used by a live connection.

Available since PostgreSQL-9.3

static VALUE
pgconn_conninfo( VALUE self )
{
        PGconn *conn = pg_get_pgconn(self);
        PQconninfoOption *options = PQconninfo( conn );
        VALUE array = pgconn_make_conninfo_array( options );

        PQconninfoFree(options);

        return array;
}
anchor
conninfo_hash()

Return the Postgres connection info structure as a Hash keyed by option keyword (as a Symbol).

See also conninfo

# File lib/pg/connection.rb, line 276
def conninfo_hash
        return self.conninfo.each_with_object({}) do |info, hash|
                hash[ info[:keyword].to_sym ] = info[:val]
        end
end
anchor
consume_input()

If input is available from the server, consume it. After calling consume_input, you can check is_busy or notifies to see if the state has changed.

static VALUE
pgconn_consume_input(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        /* returns 0 on error */
        if(PQconsumeInput(conn) == 0) {
                pgconn_close_socket_io(self);
                pg_raise_conn_error( rb_eConnectionBad, self, "%s", PQerrorMessage(conn));
        }

        return Qnil;
}
anchor
copy_data( sql [, coder] ) {|sql_result| ... } → PG::Result

Execute a copy process for transferring data to or from the server.

This issues the SQL COPY command via exec. The response to this (if there is no error in the command) is a PG::Result object that is passed to the block, bearing a status code of PGRES_COPY_OUT or PGRES_COPY_IN (depending on the specified copy direction). The application should then use put_copy_data or get_copy_data to receive or transmit data rows and should return from the block when finished.

copy_data returns another PG::Result object when the data transfer is complete. An exception is raised if some problem was encountered, so it isn’t required to make use of any of them. At this point further SQL commands can be issued via exec. (It is not possible to execute other SQL commands using the same connection while the COPY operation is in progress.)

This method ensures, that the copy process is properly terminated in case of client side or server side failures. Therefore, in case of blocking mode of operation, copy_data is preferred to raw calls of put_copy_data, get_copy_data and put_copy_end.

coder can be a PG::Coder derivation (typically PG::TextEncoder::CopyRow or PG::TextDecoder::CopyRow). This enables encoding of data fields given to put_copy_data or decoding of fields received by get_copy_data.

Example with CSV input format:

conn.exec "create table my_table (a text,b text,c text,d text)"
conn.copy_data "COPY my_table FROM STDIN CSV" do
  conn.put_copy_data "some,data,to,copy\n"
  conn.put_copy_data "more,data,to,copy\n"
end

This creates my_table and inserts two CSV rows.

The same with text format encoder PG::TextEncoder::CopyRow and Array input:

enco = PG::TextEncoder::CopyRow.new
conn.copy_data "COPY my_table FROM STDIN", enco do
  conn.put_copy_data ['some', 'data', 'to', 'copy']
  conn.put_copy_data ['more', 'data', 'to', 'copy']
end

Example with CSV output format:

conn.copy_data "COPY my_table TO STDOUT CSV" do
  while row=conn.get_copy_data
    p row
  end
end

This prints all rows of my_table to stdout:

"some,data,to,copy\n"
"more,data,to,copy\n"

The same with text format decoder PG::TextDecoder::CopyRow and Array output:

deco = PG::TextDecoder::CopyRow.new
conn.copy_data "COPY my_table TO STDOUT", deco do
  while row=conn.get_copy_data
    p row
  end
end

This receives all rows of my_table as ruby array:

["some", "data", "to", "copy"]
["more", "data", "to", "copy"]
# File lib/pg/connection.rb, line 163
def copy_data( sql, coder=nil )
        raise PG::NotInBlockingMode.new("copy_data can not be used in nonblocking mode", connection: self) if nonblocking?
        res = exec( sql )

        case res.result_status
        when PGRES_COPY_IN
                begin
                        if coder
                                old_coder = self.encoder_for_put_copy_data
                                self.encoder_for_put_copy_data = coder
                        end
                        yield res
                rescue Exception => err
                        errmsg = "%s while copy data: %s" % [ err.class.name, err.message ]
                        put_copy_end( errmsg )
                        get_result
                        raise
                else
                        put_copy_end
                        get_last_result
                ensure
                        self.encoder_for_put_copy_data = old_coder if coder
                end

        when PGRES_COPY_OUT
                begin
                        if coder
                                old_coder = self.decoder_for_get_copy_data
                                self.decoder_for_get_copy_data = coder
                        end
                        yield res
                rescue Exception => err
                        cancel
                        begin
                                while get_copy_data
                                end
                        rescue PG::Error
                                # Ignore error in cleanup to avoid losing original exception
                        end
                        while get_result
                        end
                        raise err
                else
                        res = get_last_result
                        if !res || res.result_status != PGRES_COMMAND_OK
                                while get_copy_data
                                end
                                while get_result
                                end
                                raise PG::NotAllCopyDataRetrieved.new("Not all COPY data retrieved", connection: self)
                        end
                        res
                ensure
                        self.decoder_for_get_copy_data = old_coder if coder
                end

        else
                raise ArgumentError, "SQL command is no COPY statement: #{sql}"
        end
end
anchor
db()

Returns the connected database name.

static VALUE
pgconn_db(VALUE self)
{
        char *db = PQdb(pg_get_pgconn(self));
        if (!db) return Qnil;
        return rb_str_new2(db);
}
anchor
decoder_for_get_copy_data → PG::Coder

Returns the default coder object that is currently set for type casting of received data by get_copy_data .

Returns either:

  • a kind of PG::Coder

  • nil - type encoding is disabled, returned data will be a String.

static VALUE
pgconn_decoder_for_get_copy_data_get(VALUE self)
{
        t_pg_connection *this = pg_get_connection( self );

        return this->decoder_for_get_copy_data;
}
anchor
decoder_for_get_copy_data = decoder

Set the default coder that is used for type casting of received data by get_copy_data .

decoder can be:

  • a kind of PG::Coder

  • nil - disable type decoding, returned data will be a String.

static VALUE
pgconn_decoder_for_get_copy_data_set(VALUE self, VALUE decoder)
{
        t_pg_connection *this = pg_get_connection( self );

        if( decoder != Qnil ){
                t_pg_coder *co;
                UNUSED(co);
                /* Check argument type */
                TypedData_Get_Struct(decoder, t_pg_coder, &pg_coder_type, co);
        }
        this->decoder_for_get_copy_data = decoder;

        return decoder;
}
anchor
describe_portal( portal_name ) → PG::Result

Retrieve information about the portal portal_name.

See also corresponding libpq function.

static VALUE
pgconn_async_describe_portal(VALUE self, VALUE portal)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        pgconn_send_describe_portal( self, portal );
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_describe_portal
anchor
describe_prepared( statement_name ) → PG::Result

Retrieve information about the prepared statement statement_name.

See also corresponding libpq function.

static VALUE
pgconn_async_describe_prepared(VALUE self, VALUE stmt_name)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        pgconn_send_describe_prepared( self, stmt_name );
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_describe_prepared
anchor
discard_results()

Silently discard any prior query result that application didn’t eat. This is done prior of Connection#exec and sibling methods and can be called explicitly when using the async API.

static VALUE
pgconn_discard_results(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        VALUE socket_io;

        if( PQtransactionStatus(conn) == PQTRANS_IDLE ) {
                return Qnil;
        }

        socket_io = pgconn_socket_io(self);

        for(;;) {
                PGresult *cur;
                int status;

                /* pgconn_block() raises an exception in case of errors.
                * To avoid this call pg_rb_io_wait() and PQconsumeInput() without rb_raise().
                */
                while( gvl_PQisBusy(conn) ){
                        pg_rb_io_wait(socket_io, RB_INT2NUM(PG_RUBY_IO_READABLE), Qnil);
                        if ( PQconsumeInput(conn) == 0 ) {
                                pgconn_close_socket_io(self);
                                return Qfalse;
                        }
                }

                cur = gvl_PQgetResult(conn);
                if( cur == NULL) break;

                status = PQresultStatus(cur);
                PQclear(cur);
                if (status == PGRES_COPY_IN){
                        gvl_PQputCopyEnd(conn, "COPY terminated by new PQexec");
                }
                if (status == PGRES_COPY_OUT){
                        for(;;) {
                                char *buffer = NULL;
                                int st = gvl_PQgetCopyData(conn, &buffer, 1);
                                if( st == 0 ) {
                                        /* would block -> wait for readable data */
                                        pg_rb_io_wait(socket_io, RB_INT2NUM(PG_RUBY_IO_READABLE), Qnil);
                                        if ( PQconsumeInput(conn) == 0 ) {
                                                pgconn_close_socket_io(self);
                                                return Qfalse;
                                        }
                                } else if( st > 0 ) {
                                        /* some data retrieved -> discard it */
                                        PQfreemem(buffer);
                                } else {
                                        /* no more data */
                                        break;
                                }
                        }
                }
        }

        return Qtrue;
}
anchor
encoder_for_put_copy_data → PG::Coder

Returns the default coder object that is currently set for type casting of parameters to put_copy_data .

Returns either:

  • a kind of PG::Coder

  • nil - type encoding is disabled, data must be a String.

static VALUE
pgconn_encoder_for_put_copy_data_get(VALUE self)
{
        t_pg_connection *this = pg_get_connection( self );

        return this->encoder_for_put_copy_data;
}
anchor
encoder_for_put_copy_data = encoder

Set the default coder that is used for type casting of parameters to put_copy_data .

encoder can be:

  • a kind of PG::Coder

  • nil - disable type encoding, data must be a String.

static VALUE
pgconn_encoder_for_put_copy_data_set(VALUE self, VALUE encoder)
{
        t_pg_connection *this = pg_get_connection( self );

        if( encoder != Qnil ){
                t_pg_coder *co;
                UNUSED(co);
                /* Check argument type */
                TypedData_Get_Struct(encoder, t_pg_coder, &pg_coder_type, co);
        }
        this->encoder_for_put_copy_data = encoder;

        return encoder;
}
anchor
encrypt_password( password, username, algorithm=nil ) → String

This function is intended to be used by client applications that wish to send commands like ALTER USER joe PASSWORD 'pwd'. It is good practice not to send the original cleartext password in such a command, because it might be exposed in command logs, activity displays, and so on. Instead, use this function to convert the password to encrypted form before it is sent.

The password and username arguments are the cleartext password, and the SQL name of the user it is for. algorithm specifies the encryption algorithm to use to encrypt the password. Currently supported algorithms are md5 and scram-sha-256 (on and off are also accepted as aliases for md5, for compatibility with older server versions). Note that support for scram-sha-256 was introduced in PostgreSQL version 10, and will not work correctly with older server versions. If algorithm is omitted or nil, this function will query the server for the current value of the password_encryption setting. That can block, and will fail if the current transaction is aborted, or if the connection is busy executing another query. If you wish to use the default algorithm for the server but want to avoid blocking, query password_encryption yourself before calling encrypt_password, and pass that value as the algorithm.

Return value is the encrypted password. The caller can assume the string doesn’t contain any special characters that would require escaping.

Available since PostgreSQL-10. See also corresponding libpq function.

# File lib/pg/connection.rb, line 458
def encrypt_password( password, username, algorithm=nil )
        algorithm ||= exec("SHOW password_encryption").getvalue(0,0)
        sync_encrypt_password(password, username, algorithm)
end
Also aliased as: async_encrypt_password
anchor
enter_pipeline_mode → nil

Causes a connection to enter pipeline mode if it is currently idle or already in pipeline mode.

Raises PG::Error and has no effect if the connection is not currently idle, i.e., it has a result ready, or it is waiting for more input from the server, etc. This function does not actually send anything to the server, it just changes the libpq connection state.

Available since PostgreSQL-14

static VALUE
pgconn_enter_pipeline_mode(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        int res = PQenterPipelineMode(conn);
        if( res != 1 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return Qnil;
}
anchor
error_message → String

Returns the error message most recently generated by an operation on the connection.

Nearly all libpq functions will set a message for conn.error_message if they fail. Note that by libpq convention, a nonempty error_message result can consist of multiple lines, and will include a trailing newline.

static VALUE
pgconn_error_message(VALUE self)
{
        char *error = PQerrorMessage(pg_get_pgconn(self));
        if (!error) return Qnil;
        return rb_str_new2(error);
}
anchor
escape(p1)

Returns a SQL-safe version of the String str. This is the preferred way to make strings safe for inclusion in SQL queries.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

Character encoding of escaped string will be equal to client encoding of connection.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

See also convenience functions escape_literal and escape_identifier which also add proper quotes around the string.

Alias for: escape_string
anchor
escape_bytea( string ) → String

Escapes binary data for use within an SQL command with the type bytea.

Certain byte values must be escaped (but all byte values may be escaped) when used as part of a bytea literal in an SQL statement. In general, to escape a byte, it is converted into the three digit octal number equal to the octet value, and preceded by two backslashes. The single quote (‘) and backslash () characters have special alternative escape sequences. escape_bytea performs this operation, escaping only the minimally required bytes.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

static VALUE
pgconn_s_escape_bytea(VALUE self, VALUE str)
{
        unsigned char *from, *to;
        size_t from_len, to_len;
        VALUE ret;

        Check_Type(str, T_STRING);
        from      = (unsigned char*)RSTRING_PTR(str);
        from_len  = RSTRING_LEN(str);

        if ( rb_obj_is_kind_of(self, rb_cPGconn) ) {
                to = PQescapeByteaConn(pg_get_pgconn(self), from, from_len, &to_len);
        } else {
                to = PQescapeBytea( from, from_len, &to_len);
        }

        ret = rb_str_new((char*)to, to_len - 1);
        PQfreemem(to);
        return ret;
}
Also aliased as: escape_bytea
anchor
escape_identifier( str ) → String

Escape an arbitrary String str as an identifier.

This method does the same as quote_ident with a String argument, but it doesn’t support an Array argument and it makes use of libpq to process the string.

static VALUE
pgconn_escape_identifier(VALUE self, VALUE string)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        char *escaped = NULL;
        VALUE result = Qnil;
        int enc_idx = this->enc_idx;

        StringValueCStr(string);
        if( ENCODING_GET(string) != enc_idx ){
                string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
        }

        escaped = PQescapeIdentifier(this->pgconn, RSTRING_PTR(string), RSTRING_LEN(string));
        if (escaped == NULL)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(this->pgconn));

        result = rb_str_new2(escaped);
        PQfreemem(escaped);
        PG_ENCODING_SET_NOCHECK(result, enc_idx);

        return result;
}
anchor
escape_literal( str ) → String

Escape an arbitrary String str as a literal.

See also PG::TextEncoder::QuotedLiteral for a type cast integrated version of this function.

static VALUE
pgconn_escape_literal(VALUE self, VALUE string)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        char *escaped = NULL;
        VALUE result = Qnil;
        int enc_idx = this->enc_idx;

        StringValueCStr(string);
        if( ENCODING_GET(string) != enc_idx ){
                string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
        }

        escaped = PQescapeLiteral(this->pgconn, RSTRING_PTR(string), RSTRING_LEN(string));
        if (escaped == NULL)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(this->pgconn));

        result = rb_str_new2(escaped);
        PQfreemem(escaped);
        PG_ENCODING_SET_NOCHECK(result, enc_idx);

        return result;
}
anchor
escape_string( str ) -> String

Returns a SQL-safe version of the String str. This is the preferred way to make strings safe for inclusion in SQL queries.

Consider using exec_params, which avoids the need for passing values inside of SQL commands.

Character encoding of escaped string will be equal to client encoding of connection.

NOTE: This class version of this method can only be used safely in client programs that use a single PostgreSQL connection at a time (in this case it can find out what it needs to know “behind the scenes”). It might give the wrong results if used in programs that use multiple database connections; use the same method on the connection object in such cases.

See also convenience functions escape_literal and escape_identifier which also add proper quotes around the string.

static VALUE
pgconn_s_escape(VALUE self, VALUE string)
{
        size_t size;
        int error;
        VALUE result;
        int enc_idx;
        int singleton = !rb_obj_is_kind_of(self, rb_cPGconn);

        StringValueCStr(string);
        enc_idx = singleton ? ENCODING_GET(string) : pg_get_connection(self)->enc_idx;
        if( ENCODING_GET(string) != enc_idx ){
                string = rb_str_export_to_enc(string, rb_enc_from_index(enc_idx));
        }

        result = rb_str_new(NULL, RSTRING_LEN(string) * 2 + 1);
        PG_ENCODING_SET_NOCHECK(result, enc_idx);
        if( !singleton ) {
                size = PQescapeStringConn(pg_get_pgconn(self), RSTRING_PTR(result),
                        RSTRING_PTR(string), RSTRING_LEN(string), &error);
                if(error)
                        pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(pg_get_pgconn(self)));

        } else {
                size = PQescapeString(RSTRING_PTR(result), RSTRING_PTR(string), RSTRING_LEN(string));
        }
        rb_str_set_len(result, size);

        return result;
}
Also aliased as: escape_string , escape
anchor
exec(sql) → PG::Result
exec(sql) {|pg_result| block }

Sends SQL query request specified by sql to PostgreSQL. On success, it returns a PG::Result instance with all result rows and columns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call exec_params for you. New code should explicitly use exec_params if argument placeholders are used.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

exec is an alias for async_exec which is almost identical to sync_exec . sync_exec is implemented on the simpler synchronous command processing API of libpq, whereas async_exec is implemented on the asynchronous API and on ruby’s IO mechanisms. Only async_exec is compatible to Fiber.scheduler based asynchronous IO processing introduced in ruby-3.0. Both methods ensure that other threads can process while waiting for the server to complete the request, but sync_exec blocks all signals to be processed until the query is finished. This is most notably visible by a delayed reaction to Control+C. It’s not recommended to use explicit sync or async variants but exec instead, unless you have a good reason to do so.

See also corresponding libpq function.

static VALUE
pgconn_async_exec(int argc, VALUE *argv, VALUE self)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        pgconn_send_query( argc, argv, self );
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_exec
anchor
exec_params(sql, params [, result_format [, type_map ]] ) → nil
exec_params(sql, params [, result_format [, type_map ]] ) {|pg_result| block }

Sends SQL query request specified by sql to PostgreSQL using placeholders for parameters.

Returns a PG::Result instance on success. On failure, it raises a PG::Error.

params is an array of the bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :type   => Integer (oid of type of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :type => 0, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

The primary advantage of exec_params over exec is that parameter values can be separated from the command string, thus avoiding the need for tedious and error-prone quoting and escaping. Unlike exec, exec_params allows at most one SQL command in the given string. (There can be semicolons in it, but not more than one nonempty command.) This is a limitation of the underlying protocol, but has some usefulness as an extra defense against SQL-injection attacks.

See also corresponding libpq function.

static VALUE
pgconn_async_exec_params(int argc, VALUE *argv, VALUE self)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        /* If called with no or nil parameters, use PQsendQuery for compatibility */
        if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                pg_deprecated(3, ("forwarding async_exec_params to async_exec is deprecated"));
                pgconn_send_query( argc, argv, self );
        } else {
                pgconn_send_query_params( argc, argv, self );
        }
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_exec_params
anchor
exec_prepared(statement_name [, params, result_format[, type_map]] ) → PG::Result
exec_prepared(statement_name [, params, result_format[, type_map]] ) {|pg_result| block }

Execute prepared named statement specified by statement_name. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

params is an array of the optional bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec_prepared returns the value of the block.

See also corresponding libpq function.

static VALUE
pgconn_async_exec_prepared(int argc, VALUE *argv, VALUE self)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        pgconn_send_query_prepared( argc, argv, self );
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_exec_prepared
anchor
exit_pipeline_mode → nil

Causes a connection to exit pipeline mode if it is currently in pipeline mode with an empty queue and no pending results.

Takes no action if not in pipeline mode. Raises PG::Error if the current statement isn’t finished processing, or PQgetResult has not been called to collect results from all previously sent query.

Available since PostgreSQL-14

static VALUE
pgconn_exit_pipeline_mode(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        int res = PQexitPipelineMode(conn);
        if( res != 1 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return Qnil;
}
anchor
external_encoding() → Encoding

Return the server_encoding of the connected database as a Ruby Encoding object. The SQL_ASCII encoding is mapped to to ASCII_8BIT.

static VALUE
pgconn_external_encoding(VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        rb_encoding *enc = NULL;
        const char *pg_encname = NULL;

        pg_encname = PQparameterStatus( this->pgconn, "server_encoding" );
        enc = pg_get_pg_encname_as_rb_encoding( pg_encname );
        return rb_enc_from_encoding( enc );
}
anchor
field_name_type → Symbol

Get type of field names.

See description at field_name_type=

static VALUE
pgconn_field_name_type_get(VALUE self)
{
        t_pg_connection *this = pg_get_connection( self );

        if( this->flags & PG_RESULT_FIELD_NAMES_SYMBOL ){
                return sym_symbol;
        } else if( this->flags & PG_RESULT_FIELD_NAMES_STATIC_SYMBOL ){
                return sym_static_symbol;
        } else {
                return sym_string;
        }
}
anchor
field_name_type = Symbol

Set default type of field names of results retrieved by this connection. It can be set to one of:

  • :string to use String based field names

  • :symbol to use Symbol based field names

The default is :string .

Settings the type of field names affects only future results.

See further description at PG::Result#field_name_type=

static VALUE
pgconn_field_name_type_set(VALUE self, VALUE sym)
{
        t_pg_connection *this = pg_get_connection( self );

        this->flags &= ~PG_RESULT_FIELD_NAMES_MASK;
        if( sym == sym_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_SYMBOL;
        else if ( sym == sym_static_symbol ) this->flags |= PG_RESULT_FIELD_NAMES_STATIC_SYMBOL;
        else if ( sym == sym_string );
        else rb_raise(rb_eArgError, "invalid argument %+"PRIsVALUE, sym);

        return sym;
}
anchor
finish

Closes the backend connection.

static VALUE
pgconn_finish( VALUE self )
{
        t_pg_connection *this = pg_get_connection_safe( self );

        pgconn_close_socket_io( self );
        PQfinish( this->pgconn );
        this->pgconn = NULL;
        return Qnil;
}
Also aliased as: close
anchor
finished? → boolean

Returns true if the backend connection has been closed.

static VALUE
pgconn_finished_p( VALUE self )
{
        t_pg_connection *this = pg_get_connection( self );
        if ( this->pgconn ) return Qfalse;
        return Qtrue;
}
anchor
flush() → Boolean

Attempts to flush any queued output data to the server. Returns true if data is successfully flushed, false if not. It can only return false if connection is in nonblocking mode. Raises PG::Error if some other failure occurred.

static VALUE
pgconn_async_flush(VALUE self)
{
        while( pgconn_sync_flush(self) == Qfalse ){
                /* wait for the socket to become read- or write-ready */
                int events;
                VALUE socket_io = pgconn_socket_io(self);
                events = RB_NUM2INT(pg_rb_io_wait(socket_io, RB_INT2NUM(PG_RUBY_IO_READABLE | PG_RUBY_IO_WRITABLE), Qnil));

                if (events & PG_RUBY_IO_READABLE)
                        pgconn_consume_input(self);
        }
        return Qtrue;
}
Also aliased as: async_flush
anchor
get_client_encoding() → String

Returns the client encoding as a String.

static VALUE
pgconn_get_client_encoding(VALUE self)
{
        char *encoding = (char *)pg_encoding_to_char(PQclientEncoding(pg_get_pgconn(self)));
        return rb_str_new2(encoding);
}
anchor
get_copy_data( [ nonblock = false [, decoder = nil ]] ) → Object

Return one row of data, nil if the copy is done, or false if the call would block (only possible if nonblock is true).

If decoder is not set or nil, data is returned as binary string.

If decoder is set to a PG::Coder derivation, the return type depends on this decoder. PG::TextDecoder::CopyRow decodes the received data fields from one row of PostgreSQL’s COPY text format to an Array of Strings. Optionally the decoder can type cast the single fields to various Ruby types in one step, if PG::TextDecoder::CopyRow#type_map is set accordingly.

See also copy_data.

# File lib/pg/connection.rb, line 337
def get_copy_data(async=false, decoder=nil)
        if async
                return sync_get_copy_data(async, decoder)
        else
                while (res=sync_get_copy_data(true, decoder)) == false
                        socket_io.wait_readable
                        consume_input
                end
                return res
        end
end
Also aliased as: async_get_copy_data
anchor
get_last_result( ) → PG::Result

This function retrieves all available results on the current connection (from previously issued asynchronous commands like +send_query()+) and returns the last non-NULL result, or nil if no results are available.

If the last result contains a bad result_status, an appropriate exception is raised.

This function is similar to get_result except that it is designed to get one and only one result and that it checks the result state.

static VALUE
pgconn_async_get_last_result(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        VALUE rb_pgresult = Qnil;
        PGresult *cur, *prev;

  cur = prev = NULL;
        for(;;) {
                int status;

                /* wait for input (without blocking) before reading each result */
                wait_socket_readable(self, NULL, get_result_readable);

                cur = gvl_PQgetResult(conn);
                if (cur == NULL)
                        break;

                if (prev) PQclear(prev);
                prev = cur;

                status = PQresultStatus(cur);
                if (status == PGRES_COPY_OUT || status == PGRES_COPY_IN || status == PGRES_COPY_BOTH)
                        break;
        }

        if (prev) {
                rb_pgresult = pg_new_result( prev, self );
                pg_result_check(rb_pgresult);
        }

        return rb_pgresult;
}
Also aliased as: async_get_last_result
anchor
get_result() → PG::Result
get_result() {|pg_result| block }

Blocks waiting for the next result from a call to send_query (or another asynchronous command), and returns it. Returns nil if no more results are available.

Note: call this function repeatedly until it returns nil, or else you will not be able to issue further commands.

If the optional code block is given, it will be passed result as an argument, and the PG::Result object will automatically be cleared when the block terminates. In this instance, conn.exec returns the value of the block.

# File lib/pg/connection.rb, line 314
def get_result
        block
        sync_get_result
end
Also aliased as: async_get_result
anchor
host()

Returns the server host name of the active connection. This can be a host name, an IP address, or a directory path if the connection is via Unix socket. (The path case can be distinguished because it will always be an absolute path, beginning with / .)

If the connection parameters specified both host and hostaddr, then host will return the host information. If only hostaddr was specified, then that is returned. If multiple hosts were specified in the connection parameters, host returns the host actually connected to.

If there is an error producing the host information (perhaps if the connection has not been fully established or there was an error), it returns an empty string.

If multiple hosts were specified in the connection parameters, it is not possible to rely on the result of host until the connection is established. The status of the connection can be checked using the function Connection#status .

static VALUE
pgconn_host(VALUE self)
{
        char *host = PQhost(pg_get_pgconn(self));
        if (!host) return Qnil;
        return rb_str_new2(host);
}
anchor
hostaddr()

Returns the server IP address of the active connection. This can be the address that a host name resolved to, or an IP address provided through the hostaddr parameter. If there is an error producing the host information (perhaps if the connection has not been fully established or there was an error), it returns an empty string.

static VALUE
pgconn_hostaddr(VALUE self)
{
        char *host = PQhostaddr(pg_get_pgconn(self));
        if (!host) return Qnil;
        return rb_str_new2(host);
}
anchor
internal_encoding → Encoding

defined in Ruby 1.9 or later.

Returns:

  • an Encoding - client_encoding of the connection as a Ruby Encoding object.

  • nil - the client_encoding is ‘SQL_ASCII’

static VALUE
pgconn_internal_encoding(VALUE self)
{
        PGconn *conn = pg_get_pgconn( self );
        rb_encoding *enc = pg_conn_enc_get( conn );

        if ( enc ) {
                return rb_enc_from_encoding( enc );
        } else {
                return Qnil;
        }
}
anchor
internal_encoding = value

A wrapper of set_client_encoding. defined in Ruby 1.9 or later.

value can be one of:

  • an Encoding

  • a String - a name of Encoding

  • nil - sets the client_encoding to SQL_ASCII.

static VALUE
pgconn_internal_encoding_set(VALUE self, VALUE enc)
{
        if (NIL_P(enc)) {
                pgconn_sync_set_client_encoding( self, rb_usascii_str_new_cstr("SQL_ASCII") );
                return enc;
        }
        else if ( TYPE(enc) == T_STRING && strcasecmp("JOHAB", StringValueCStr(enc)) == 0 ) {
                pgconn_sync_set_client_encoding(self, rb_usascii_str_new_cstr("JOHAB"));
                return enc;
        }
        else {
                rb_encoding *rbenc = rb_to_encoding( enc );
                const char *name = pg_get_rb_encoding_as_pg_encoding( rbenc );

                if ( gvl_PQsetClientEncoding(pg_get_pgconn( self ), name) == -1 ) {
                        VALUE server_encoding = pgconn_external_encoding( self );
                        rb_raise( rb_eEncCompatError, "incompatible character encodings: %s and %s",
                                          rb_enc_name(rb_to_encoding(server_encoding)), name );
                }
                pgconn_set_internal_encoding_index( self );
                return enc;
        }
}
anchor
is_busy() → Boolean

Returns true if a command is busy, that is, if get_result would block. Otherwise returns false.

static VALUE
pgconn_is_busy(VALUE self)
{
        return gvl_PQisBusy(pg_get_pgconn(self)) ? Qtrue : Qfalse;
}
anchor
isnonblocking() → Boolean

Returns the blocking status of the database connection. Returns true if the connection is set to nonblocking mode and false if blocking.

# File lib/pg/connection.rb, line 385
def isnonblocking
        false
end
Also aliased as: async_isnonblocking , nonblocking?
anchor
lo_close( lo_desc ) → nil

Closes the postgres large object of lo_desc.

static VALUE
pgconn_loclose(VALUE self, VALUE in_lo_desc)
{
        PGconn *conn = pg_get_pgconn(self);
        int lo_desc = NUM2INT(in_lo_desc);

        if(lo_close(conn,lo_desc) < 0)
                pg_raise_conn_error( rb_ePGerror, self, "lo_close failed");

        return Qnil;
}
Also aliased as: loclose
anchor
lo_creat( [mode] ) → Integer

Creates a large object with mode mode. Returns a large object Oid. On failure, it raises PG::Error.

static VALUE
pgconn_locreat(int argc, VALUE *argv, VALUE self)
{
        Oid lo_oid;
        int mode;
        VALUE nmode;
        PGconn *conn = pg_get_pgconn(self);

        if (rb_scan_args(argc, argv, "01", &nmode) == 0)
                mode = INV_READ;
        else
                mode = NUM2INT(nmode);

        lo_oid = lo_creat(conn, mode);
        if (lo_oid == 0)
                pg_raise_conn_error( rb_ePGerror, self, "lo_creat failed");

        return UINT2NUM(lo_oid);
}
Also aliased as: locreat
anchor
lo_create( oid ) → Integer

Creates a large object with oid oid. Returns the large object Oid. On failure, it raises PG::Error.

static VALUE
pgconn_locreate(VALUE self, VALUE in_lo_oid)
{
        Oid ret, lo_oid;
        PGconn *conn = pg_get_pgconn(self);
        lo_oid = NUM2UINT(in_lo_oid);

        ret = lo_create(conn, lo_oid);
        if (ret == InvalidOid)
                pg_raise_conn_error( rb_ePGerror, self, "lo_create failed");

        return UINT2NUM(ret);
}
Also aliased as: locreate
anchor
lo_export( oid, file ) → nil

Saves a large object of oid to a file.

static VALUE
pgconn_loexport(VALUE self, VALUE lo_oid, VALUE filename)
{
        PGconn *conn = pg_get_pgconn(self);
        Oid oid;
        Check_Type(filename, T_STRING);

        oid = NUM2UINT(lo_oid);

        if (lo_export(conn, oid, StringValueCStr(filename)) < 0) {
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));
        }
        return Qnil;
}
Also aliased as: loexport
anchor
lo_import(file) → Integer

Import a file to a large object. Returns a large object Oid.

On failure, it raises a PG::Error.

static VALUE
pgconn_loimport(VALUE self, VALUE filename)
{
        Oid lo_oid;

        PGconn *conn = pg_get_pgconn(self);

        Check_Type(filename, T_STRING);

        lo_oid = lo_import(conn, StringValueCStr(filename));
        if (lo_oid == 0) {
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));
        }
        return UINT2NUM(lo_oid);
}
Also aliased as: loimport
anchor
lo_lseek( lo_desc, offset, whence ) → Integer

Move the large object pointer lo_desc to offset offset. Valid values for whence are SEEK_SET, SEEK_CUR, and SEEK_END. (Or 0, 1, or 2.)

static VALUE
pgconn_lolseek(VALUE self, VALUE in_lo_desc, VALUE offset, VALUE whence)
{
        PGconn *conn = pg_get_pgconn(self);
        int lo_desc = NUM2INT(in_lo_desc);
        int ret;

        if((ret = lo_lseek(conn, lo_desc, NUM2INT(offset), NUM2INT(whence))) < 0) {
                pg_raise_conn_error( rb_ePGerror, self, "lo_lseek failed");
        }

        return INT2FIX(ret);
}
Also aliased as: lolseek , lo_seek , loseek
anchor
lo_open( oid, [mode] ) → Integer

Open a large object of oid. Returns a large object descriptor instance on success. The mode argument specifies the mode for the opened large object,which is either INV_READ, or INV_WRITE.

If mode is omitted, the default is INV_READ.

static VALUE
pgconn_loopen(int argc, VALUE *argv, VALUE self)
{
        Oid lo_oid;
        int fd, mode;
        VALUE nmode, selfid;
        PGconn *conn = pg_get_pgconn(self);

        rb_scan_args(argc, argv, "11", &selfid, &nmode);
        lo_oid = NUM2UINT(selfid);
        if(NIL_P(nmode))
                mode = INV_READ;
        else
                mode = NUM2INT(nmode);

        if((fd = lo_open(conn, lo_oid, mode)) < 0) {
                pg_raise_conn_error( rb_ePGerror, self, "can't open large object: %s", PQerrorMessage(conn));
        }
        return INT2FIX(fd);
}
Also aliased as: loopen
anchor
lo_read( lo_desc, len ) → String

Attempts to read len bytes from large object lo_desc, returns resulting data.

static VALUE
pgconn_loread(VALUE self, VALUE in_lo_desc, VALUE in_len)
{
        int ret;
  PGconn *conn = pg_get_pgconn(self);
        int len = NUM2INT(in_len);
        int lo_desc = NUM2INT(in_lo_desc);
        VALUE str;
        char *buffer;

        if (len < 0)
                pg_raise_conn_error( rb_ePGerror, self, "negative length %d given", len);

        buffer = ALLOC_N(char, len);
        if((ret = lo_read(conn, lo_desc, buffer, len)) < 0)
                pg_raise_conn_error( rb_ePGerror, self, "lo_read failed");

        if(ret == 0) {
                xfree(buffer);
                return Qnil;
        }

        str = rb_str_new(buffer, ret);
        xfree(buffer);

        return str;
}
Also aliased as: loread
anchor
lo_seek(p1, p2, p3)

Move the large object pointer lo_desc to offset offset. Valid values for whence are SEEK_SET, SEEK_CUR, and SEEK_END. (Or 0, 1, or 2.)

Alias for: lo_lseek
anchor
lo_tell( lo_desc ) → Integer

Returns the current position of the large object lo_desc.

static VALUE
pgconn_lotell(VALUE self, VALUE in_lo_desc)
{
        int position;
        PGconn *conn = pg_get_pgconn(self);
        int lo_desc = NUM2INT(in_lo_desc);

        if((position = lo_tell(conn, lo_desc)) < 0)
                pg_raise_conn_error( rb_ePGerror, self, "lo_tell failed");

        return INT2FIX(position);
}
Also aliased as: lotell
anchor
lo_truncate( lo_desc, len ) → nil

Truncates the large object lo_desc to size len.

static VALUE
pgconn_lotruncate(VALUE self, VALUE in_lo_desc, VALUE in_len)
{
        PGconn *conn = pg_get_pgconn(self);
        int lo_desc = NUM2INT(in_lo_desc);
        size_t len = NUM2INT(in_len);

        if(lo_truncate(conn,lo_desc,len) < 0)
                pg_raise_conn_error( rb_ePGerror, self, "lo_truncate failed");

        return Qnil;
}
Also aliased as: lotruncate
anchor anchor
lo_write( lo_desc, buffer ) → Integer

Writes the string buffer to the large object lo_desc. Returns the number of bytes written.

static VALUE
pgconn_lowrite(VALUE self, VALUE in_lo_desc, VALUE buffer)
{
        int n;
        PGconn *conn = pg_get_pgconn(self);
        int fd = NUM2INT(in_lo_desc);

        Check_Type(buffer, T_STRING);

        if( RSTRING_LEN(buffer) < 0) {
                pg_raise_conn_error( rb_ePGerror, self, "write buffer zero string");
        }
        if((n = lo_write(conn, fd, StringValuePtr(buffer),
                                RSTRING_LEN(buffer))) < 0) {
                pg_raise_conn_error( rb_ePGerror, self, "lo_write failed: %s", PQerrorMessage(conn));
        }

        return INT2FIX(n);
}
Also aliased as: lowrite
anchor
loclose(p1)

Closes the postgres large object of lo_desc.

Alias for: lo_close
anchor
locreat(p1 = v1)

Creates a large object with mode mode. Returns a large object Oid. On failure, it raises PG::Error.

Alias for: lo_creat
anchor
locreate(p1)

Creates a large object with oid oid. Returns the large object Oid. On failure, it raises PG::Error.

Alias for: lo_create
anchor
loexport(p1, p2)

Saves a large object of oid to a file.

Alias for: lo_export
anchor
loimport(p1)

Import a file to a large object. Returns a large object Oid.

On failure, it raises a PG::Error.

Alias for: lo_import
anchor
lolseek(p1, p2, p3)

Move the large object pointer lo_desc to offset offset. Valid values for whence are SEEK_SET, SEEK_CUR, and SEEK_END. (Or 0, 1, or 2.)

Alias for: lo_lseek
anchor
loopen(p1, p2 = v2)

Open a large object of oid. Returns a large object descriptor instance on success. The mode argument specifies the mode for the opened large object,which is either INV_READ, or INV_WRITE.

If mode is omitted, the default is INV_READ.

Alias for: lo_open
anchor
loread(p1, p2)

Attempts to read len bytes from large object lo_desc, returns resulting data.

Alias for: lo_read
anchor
loseek(p1, p2, p3)

Move the large object pointer lo_desc to offset offset. Valid values for whence are SEEK_SET, SEEK_CUR, and SEEK_END. (Or 0, 1, or 2.)

Alias for: lo_lseek
anchor
lotell(p1)

Returns the current position of the large object lo_desc.

Alias for: lo_tell
anchor
lotruncate(p1, p2)

Truncates the large object lo_desc to size len.

Alias for: lo_truncate
anchor anchor
lowrite(p1, p2)

Writes the string buffer to the large object lo_desc. Returns the number of bytes written.

Alias for: lo_write
anchor
make_empty_pgresult( status ) → PG::Result

Constructs and empty PG::Result with status status. status may be one of:

  • PGRES_EMPTY_QUERY

  • PGRES_COMMAND_OK

  • PGRES_TUPLES_OK

  • PGRES_COPY_OUT

  • PGRES_COPY_IN

  • PGRES_BAD_RESPONSE

  • PGRES_NONFATAL_ERROR

  • PGRES_FATAL_ERROR

  • PGRES_COPY_BOTH

  • PGRES_SINGLE_TUPLE

  • PGRES_PIPELINE_SYNC

  • PGRES_PIPELINE_ABORTED

static VALUE
pgconn_make_empty_pgresult(VALUE self, VALUE status)
{
        PGresult *result;
        VALUE rb_pgresult;
        PGconn *conn = pg_get_pgconn(self);
        result = PQmakeEmptyPGresult(conn, NUM2INT(status));
        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);
        return rb_pgresult;
}
anchor
nonblocking?()
Alias for: isnonblocking
anchor
notifies()

Returns a hash of the unprocessed notifications. If there is no unprocessed notifier, it returns nil.

static VALUE
pgconn_notifies(VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGnotify *notification;
        VALUE hash;
        VALUE sym_relname, sym_be_pid, sym_extra;
        VALUE relname, be_pid, extra;

        sym_relname = ID2SYM(rb_intern("relname"));
        sym_be_pid = ID2SYM(rb_intern("be_pid"));
        sym_extra = ID2SYM(rb_intern("extra"));

        notification = gvl_PQnotifies(this->pgconn);
        if (notification == NULL) {
                return Qnil;
        }

        hash = rb_hash_new();
        relname = rb_str_new2(notification->relname);
        be_pid = INT2NUM(notification->be_pid);
        extra = rb_str_new2(notification->extra);
        PG_ENCODING_SET_NOCHECK( relname, this->enc_idx );
        PG_ENCODING_SET_NOCHECK( extra, this->enc_idx );

        rb_hash_aset(hash, sym_relname, relname);
        rb_hash_aset(hash, sym_be_pid, be_pid);
        rb_hash_aset(hash, sym_extra, extra);

        PQfreemem(notification);
        return hash;
}
anchor
notifies_wait(p1 = v1)

Blocks while waiting for notification(s), or until the optional timeout is reached, whichever comes first. timeout is measured in seconds and can be fractional.

Returns nil if timeout is reached, the name of the NOTIFY event otherwise. If used in block form, passes the name of the NOTIFY event, the generating pid and the optional payload string into the block.

Alias for: wait_for_notify
anchor
options()

Returns backend option string.

static VALUE
pgconn_options(VALUE self)
{
        char *options = PQoptions(pg_get_pgconn(self));
        if (!options) return Qnil;
        return rb_str_new2(options);
}
anchor
parameter_status( param_name ) → String

Returns the setting of parameter param_name, where param_name is one of

  • server_version

  • server_encoding

  • client_encoding

  • is_superuser

  • session_authorization

  • DateStyle

  • TimeZone

  • integer_datetimes

  • standard_conforming_strings

Returns nil if the value of the parameter is not known.

static VALUE
pgconn_parameter_status(VALUE self, VALUE param_name)
{
        const char *ret = PQparameterStatus(pg_get_pgconn(self), StringValueCStr(param_name));
        if(ret == NULL)
                return Qnil;
        else
                return rb_str_new2(ret);
}
anchor
pass()

Returns the authenticated password.

static VALUE
pgconn_pass(VALUE self)
{
        char *user = PQpass(pg_get_pgconn(self));
        if (!user) return Qnil;
        return rb_str_new2(user);
}
anchor
pipeline_status → Integer

Returns the current pipeline mode status of the libpq connection.

PQpipelineStatus can return one of the following values:

  • PQ_PIPELINE_ON - The libpq connection is in pipeline mode.

  • PQ_PIPELINE_OFF - The libpq connection is not in pipeline mode.

  • PQ_PIPELINE_ABORTED - The libpq connection is in pipeline mode and an error occurred while processing the current pipeline. The aborted flag is cleared when PQgetResult returns a result of type PGRES_PIPELINE_SYNC.

Available since PostgreSQL-14

static VALUE
pgconn_pipeline_status(VALUE self)
{
        int res = PQpipelineStatus(pg_get_pgconn(self));
        return INT2FIX(res);
}
anchor
pipeline_sync → nil

Marks a synchronization point in a pipeline by sending a sync message and flushing the send buffer. This serves as the delimiter of an implicit transaction and an error recovery point; see Section 34.5.1.3 of the PostgreSQL documentation.

Raises PG::Error if the connection is not in pipeline mode or sending a sync message failed.

Available since PostgreSQL-14

static VALUE
pgconn_pipeline_sync(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        int res = PQpipelineSync(conn);
        if( res != 1 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return Qnil;
}
anchor
port()

Returns the connected server port number.

static VALUE
pgconn_port(VALUE self)
{
        char* port = PQport(pg_get_pgconn(self));
        return INT2NUM(atoi(port));
}
anchor
prepare(stmt_name, sql [, param_types ] ) → PG::Result

Prepares statement sql with name name to be executed later. Returns a PG::Result instance on success. On failure, it raises a PG::Error.

param_types is an optional parameter to specify the Oids of the types of the parameters.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query.

See also corresponding libpq function.

static VALUE
pgconn_async_prepare(int argc, VALUE *argv, VALUE self)
{
        VALUE rb_pgresult = Qnil;

        pgconn_discard_results( self );
        pgconn_send_prepare( argc, argv, self );
        rb_pgresult = pgconn_async_get_last_result( self );

        if ( rb_block_given_p() ) {
                return rb_ensure( rb_yield, rb_pgresult, pg_result_clear, rb_pgresult );
        }
        return rb_pgresult;
}
Also aliased as: async_prepare
anchor
protocol_version → Integer

The 3.0 protocol will normally be used when communicating with PostgreSQL 7.4 or later servers; pre-7.4 servers support only protocol 2.0. (Protocol 1.0 is obsolete and not supported by libpq.)

static VALUE
pgconn_protocol_version(VALUE self)
{
        return INT2NUM(PQprotocolVersion(pg_get_pgconn(self)));
}
anchor
put_copy_data( buffer [, encoder] ) → Boolean

Transmits buffer as copy data to the server. Returns true if the data was sent, false if it was not sent (false is only possible if the connection is in nonblocking mode, and this command would block).

encoder can be a PG::Coder derivation (typically PG::TextEncoder::CopyRow). This encodes the data fields given as buffer from an Array of Strings to PostgreSQL’s COPY text format inclusive proper escaping. Optionally the encoder can type cast the fields from various Ruby types in one step, if PG::TextEncoder::CopyRow#type_map is set accordingly.

Raises an exception if an error occurs.

See also copy_data.

# File lib/pg/connection.rb, line 409
def put_copy_data(buffer, encoder=nil)
        until res=sync_put_copy_data(buffer, encoder)
                res = flush
        end
        res
end
Also aliased as: async_put_copy_data
anchor
put_copy_end( [ error_message ] ) → Boolean

Sends end-of-data indication to the server.

error_message is an optional parameter, and if set, forces the COPY command to fail with the string error_message.

Returns true if the end-of-data was sent, false* if it was not sent (false is only possible if the connection is in nonblocking mode, and this command would block).

# File lib/pg/connection.rb, line 429
def put_copy_end(*args)
        until sync_put_copy_end(*args)
                flush
        end
        flush
end
Also aliased as: async_put_copy_end
anchor
quote_ident( str ) → String
quote_ident( array ) → String
PG::Connection.quote_ident( str ) → String
PG::Connection.quote_ident( array ) → String

Returns a string that is safe for inclusion in a SQL query as an identifier. Note: this is not a quote function for values, but for identifiers.

For example, in a typical SQL query: SELECT FOO FROM MYTABLE The identifier FOO is folded to lower case, so it actually means foo. If you really want to access the case-sensitive field name FOO, use this function like conn.quote_ident('FOO'), which will return "FOO" (with double-quotes). PostgreSQL will see the double-quotes, and it will not fold to lower case.

Similarly, this function also protects against special characters, and other things that might allow SQL injection if the identifier comes from an untrusted source.

If the parameter is an Array, then all it’s values are separately quoted and then joined by a “.” character. This can be used for identifiers in the form “schema”.“table”.“column” .

This method is functional identical to the encoder PG::TextEncoder::Identifier .

If the instance method form is used and the input string character encoding is different to the connection encoding, then the string is converted to this encoding, so that the returned string is always encoded as PG::Connection#internal_encoding .

In the singleton form (PG::Connection.quote_ident) the character encoding of the result string is set to the character encoding of the input string.

static VALUE
pgconn_s_quote_ident(VALUE self, VALUE str_or_array)
{
        VALUE ret;
        int enc_idx;

        if( rb_obj_is_kind_of(self, rb_cPGconn) ){
                enc_idx = pg_get_connection(self)->enc_idx;
        }else{
                enc_idx = RB_TYPE_P(str_or_array, T_STRING) ? ENCODING_GET( str_or_array ) : rb_ascii8bit_encindex();
        }
        pg_text_enc_identifier(NULL, str_or_array, NULL, &ret, enc_idx);

        return ret;
}
Also aliased as: quote_ident
anchor
reset()

Resets the backend connection. This method closes the backend connection and tries to re-connect.

# File lib/pg/connection.rb, line 470
def reset
        reset_start
        async_connect_or_reset(:reset_poll)
        self
end
Also aliased as: async_reset
anchor
reset_poll → Integer

Checks the status of a connection reset operation. See connect_start and connect_poll for usage information and return values.

static VALUE
pgconn_reset_poll(VALUE self)
{
        PostgresPollingStatusType status;
        status = gvl_PQresetPoll(pg_get_pgconn(self));

        pgconn_close_socket_io(self);

        return INT2FIX((int)status);
}
anchor
reset_start() → nil

Initiate a connection reset in a nonblocking manner. This will close the current connection and attempt to reconnect using the same connection parameters. Use reset_poll to check the status of the connection reset.

static VALUE
pgconn_reset_start(VALUE self)
{
        pgconn_close_socket_io( self );
        if(gvl_PQresetStart(pg_get_pgconn(self)) == 0)
                pg_raise_conn_error( rb_eUnableToSend, self, "reset has failed");
        return Qnil;
}
anchor
send_describe_portal( portal_name ) → nil

Asynchronously send command to the server. Does not block. Use in combination with conn.get_result.

static VALUE
pgconn_send_describe_portal(VALUE self, VALUE portal)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        /* returns 0 on failure */
        if(gvl_PQsendDescribePortal(this->pgconn, pg_cstr_enc(portal, this->enc_idx)) == 0)
                pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));

        pgconn_wait_for_flush( self );
        return Qnil;
}
anchor
send_describe_prepared( statement_name ) → nil

Asynchronously send command to the server. Does not block. Use in combination with conn.get_result.

static VALUE
pgconn_send_describe_prepared(VALUE self, VALUE stmt_name)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        /* returns 0 on failure */
        if(gvl_PQsendDescribePrepared(this->pgconn, pg_cstr_enc(stmt_name, this->enc_idx)) == 0)
                pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));

        pgconn_wait_for_flush( self );
        return Qnil;
}
anchor
pipeline_sync → nil

Sends a request for the server to flush its output buffer.

The server flushes its output buffer automatically as a result of Connection#pipeline_sync being called, or on any request when not in pipeline mode. This function is useful to cause the server to flush its output buffer in pipeline mode without establishing a synchronization point. Note that the request is not itself flushed to the server automatically; use Connection#flush if necessary.

Available since PostgreSQL-14

static VALUE
pgconn_send_flush_request(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        int res = PQsendFlushRequest(conn);
        if( res != 1 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return Qnil;
}
anchor
send_prepare( stmt_name, sql [, param_types ] ) → nil

Prepares statement sql with name name to be executed later. Sends prepare command asynchronously, and returns immediately. On failure, it raises a PG::Error.

param_types is an optional parameter to specify the Oids of the types of the parameters.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query.

static VALUE
pgconn_send_prepare(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        int result;
        VALUE name, command, in_paramtypes;
        VALUE param;
        int i = 0;
        int nParams = 0;
        Oid *paramTypes = NULL;
        const char *name_cstr;
        const char *command_cstr;
        int enc_idx = this->enc_idx;

        rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
        name_cstr = pg_cstr_enc(name, enc_idx);
        command_cstr = pg_cstr_enc(command, enc_idx);

        if(! NIL_P(in_paramtypes)) {
                Check_Type(in_paramtypes, T_ARRAY);
                nParams = (int)RARRAY_LEN(in_paramtypes);
                paramTypes = ALLOC_N(Oid, nParams);
                for(i = 0; i < nParams; i++) {
                        param = rb_ary_entry(in_paramtypes, i);
                        if(param == Qnil)
                                paramTypes[i] = 0;
                        else
                                paramTypes[i] = NUM2UINT(param);
                }
        }
        result = gvl_PQsendPrepare(this->pgconn, name_cstr, command_cstr, nParams, paramTypes);

        xfree(paramTypes);

        if(result == 0) {
                pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));
        }
        pgconn_wait_for_flush( self );
        return Qnil;
}
anchor
send_query(sql) → nil

Sends SQL query request specified by sql to PostgreSQL for asynchronous processing, and immediately returns. On failure, it raises a PG::Error.

For backward compatibility, if you pass more than one parameter to this method, it will call send_query_params for you. New code should explicitly use send_query_params if argument placeholders are used.

static VALUE
pgconn_send_query(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );

        /* If called with no or nil parameters, use PQexec for compatibility */
        if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                if(gvl_PQsendQuery(this->pgconn, pg_cstr_enc(argv[0], this->enc_idx)) == 0)
                        pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));

                pgconn_wait_for_flush( self );
                return Qnil;
        }

        pg_deprecated(2, ("forwarding async_exec to async_exec_params and send_query to send_query_params is deprecated"));

        /* If called with parameters, and optionally result_format,
         * use PQsendQueryParams
         */
        return pgconn_send_query_params( argc, argv, self);
}
anchor
send_query_params(sql, params [, result_format [, type_map ]] ) → nil

Sends SQL query request specified by sql to PostgreSQL for asynchronous processing, and immediately returns. On failure, it raises a PG::Error.

params is an array of the bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :type   => Integer (oid of type of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :type => 0, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

If the types are not specified, they will be inferred by PostgreSQL. Instead of specifying type oids, it’s recommended to simply add explicit casts in the query to ensure that the right type is used.

For example: “SELECT $1::int”

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

static VALUE
pgconn_send_query_params(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        int result;
        VALUE command, in_res_fmt;
        int nParams;
        int resultFormat;
        struct query_params_data paramsData = { this->enc_idx };

        rb_scan_args(argc, argv, "22", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 1;

        pgconn_query_assign_typemap( self, &paramsData );
        resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
        nParams = alloc_query_params( &paramsData );

        result = gvl_PQsendQueryParams(this->pgconn, pg_cstr_enc(command, paramsData.enc_idx), nParams, paramsData.types,
                (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats, resultFormat);

        free_query_params( &paramsData );

        if(result == 0)
                pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));

        pgconn_wait_for_flush( self );
        return Qnil;
}
anchor
send_query_prepared( statement_name [, params, result_format[, type_map ]] )
→ nil

Execute prepared named statement specified by statement_name asynchronously, and returns immediately. On failure, it raises a PG::Error.

params is an array of the optional bind parameters for the SQL query. Each element of the params array may be either:

a hash of the form:
  {:value  => String (value of bind parameter)
   :format => Integer (0 for text, 1 for binary)
  }
or, it may be a String. If it is a string, that is equivalent to the hash:
  { :value => <string value>, :format => 0 }

PostgreSQL bind parameters are represented as $1, $2, $3, etc., inside the SQL query. The 0th element of the params array is bound to $1, the 1st element is bound to $2, etc. nil is treated as NULL.

The optional result_format should be 0 for text results, 1 for binary.

type_map can be a PG::TypeMap derivation (such as PG::BasicTypeMapForQueries). This will type cast the params from various Ruby types before transmission based on the encoders defined by the type map. When a type encoder is used the format and oid of a given bind parameter are retrieved from the encoder instead out of the hash form described above.

static VALUE
pgconn_send_query_prepared(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        int result;
        VALUE name, in_res_fmt;
        int nParams;
        int resultFormat;
        struct query_params_data paramsData = { this->enc_idx };

        rb_scan_args(argc, argv, "13", &name, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 0;

        if(NIL_P(paramsData.params)) {
                paramsData.params = rb_ary_new2(0);
        }
        pgconn_query_assign_typemap( self, &paramsData );

        resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
        nParams = alloc_query_params( &paramsData );

        result = gvl_PQsendQueryPrepared(this->pgconn, pg_cstr_enc(name, paramsData.enc_idx), nParams,
                (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats,
                resultFormat);

        free_query_params( &paramsData );

        if(result == 0)
                pg_raise_conn_error( rb_eUnableToSend, self, "%s", PQerrorMessage(this->pgconn));

        pgconn_wait_for_flush( self );
        return Qnil;
}
anchor
server_version → Integer

The number is formed by converting the major, minor, and revision numbers into two-decimal-digit numbers and appending them together. For example, version 7.4.2 will be returned as 70402, and version 8.1 will be returned as 80100 (leading zeroes are not shown). Zero is returned if the connection is bad.

static VALUE
pgconn_server_version(VALUE self)
{
        return INT2NUM(PQserverVersion(pg_get_pgconn(self)));
}
anchor
set_client_encoding( encoding )

Sets the client encoding to the encoding String.

static VALUE
pgconn_async_set_client_encoding(VALUE self, VALUE encname)
{
        VALUE query_format, query;

        Check_Type(encname, T_STRING);
        query_format = rb_str_new_cstr("set client_encoding to '%s'");
        query = rb_funcall(query_format, rb_intern("%"), 1, encname);

        pgconn_async_exec(1, &query, self);
        pgconn_set_internal_encoding_index( self );

        return Qnil;
}
anchor
set_default_encoding() → Encoding

If Ruby has its Encoding.default_internal set, set PostgreSQL’s client_encoding to match. Returns the new Encoding, or nil if the default internal encoding wasn’t set.

static VALUE
pgconn_set_default_encoding( VALUE self )
{
        PGconn *conn = pg_get_pgconn( self );
        rb_encoding *enc;
        const char *encname;

        if (( enc = rb_default_internal_encoding() )) {
                encname = pg_get_rb_encoding_as_pg_encoding( enc );
                if ( pgconn_set_client_encoding_async(self, rb_str_new_cstr(encname)) != 0 )
                        rb_warning( "Failed to set the default_internal encoding to %s: '%s'",
                                 encname, PQerrorMessage(conn) );
                return rb_enc_from_encoding( enc );
        } else {
                pgconn_set_internal_encoding_index( self );
                return Qnil;
        }
}
anchor
set_error_context_visibility( context_visibility ) → Integer

Sets connection’s context display mode to context_visibility and returns the previous setting. Available settings are:

  • PQSHOW_CONTEXT_NEVER

  • PQSHOW_CONTEXT_ERRORS

  • PQSHOW_CONTEXT_ALWAYS

This mode controls whether the CONTEXT field is included in messages (unless the verbosity setting is TERSE, in which case CONTEXT is never shown). The NEVER mode never includes CONTEXT, while ALWAYS always includes it if available. In ERRORS mode (the default), CONTEXT fields are included only for error messages, not for notices and warnings.

Changing this mode does not affect the messages available from already-existing PG::Result objects, only subsequently-created ones. (But see PG::Result#verbose_error_message if you want to print a previous error with a different display mode.)

See also corresponding libpq function.

Available since PostgreSQL-9.6

static VALUE
pgconn_set_error_context_visibility(VALUE self, VALUE in_context_visibility)
{
        PGconn *conn = pg_get_pgconn(self);
        PGContextVisibility context_visibility = NUM2INT(in_context_visibility);
        return INT2FIX(PQsetErrorContextVisibility(conn, context_visibility));
}
anchor
set_error_verbosity( verbosity ) → Integer

Sets connection’s verbosity to verbosity and returns the previous setting. Available settings are:

  • PQERRORS_TERSE

  • PQERRORS_DEFAULT

  • PQERRORS_VERBOSE

  • PQERRORS_SQLSTATE

Changing the verbosity does not affect the messages available from already-existing PG::Result objects, only subsequently-created ones. (But see PG::Result#verbose_error_message if you want to print a previous error with a different verbosity.)

See also corresponding libpq function.

static VALUE
pgconn_set_error_verbosity(VALUE self, VALUE in_verbosity)
{
        PGconn *conn = pg_get_pgconn(self);
        PGVerbosity verbosity = NUM2INT(in_verbosity);
        return INT2FIX(PQsetErrorVerbosity(conn, verbosity));
}
anchor
set_notice_processor {|message| ... } → Proc

See set_notice_receiver for the description of what this and the notice_processor methods do.

This function takes a new block to act as the notice processor and returns the Proc object previously set, or nil if it was previously the default. The block should accept a single String object.

If you pass no arguments, it will reset the handler to the default.

static VALUE
pgconn_set_notice_processor(VALUE self)
{
        VALUE proc, old_proc;
        t_pg_connection *this = pg_get_connection_safe( self );

        /* If default_notice_processor is unset, assume that the current
         * notice processor is the default, and save it to a global variable.
         * This should not be a problem because the default processor is
         * always the same, so won't vary among connections.
         */
        if(default_notice_processor == NULL)
                default_notice_processor = PQsetNoticeProcessor(this->pgconn, NULL, NULL);

        old_proc = this->notice_receiver;
        if( rb_block_given_p() ) {
                proc = rb_block_proc();
                PQsetNoticeProcessor(this->pgconn, gvl_notice_processor_proxy, (void *)self);
        } else {
                /* if no block is given, set back to default */
                proc = Qnil;
                PQsetNoticeProcessor(this->pgconn, default_notice_processor, NULL);
        }

        this->notice_receiver = proc;
        return old_proc;
}
anchor
set_notice_receiver {|result| ... } → Proc

Notice and warning messages generated by the server are not returned by the query execution functions, since they do not imply failure of the query. Instead they are passed to a notice handling function, and execution continues normally after the handler returns. The default notice handling function prints the message on stderr, but the application can override this behavior by supplying its own handling function.

For historical reasons, there are two levels of notice handling, called the notice receiver and notice processor. The default behavior is for the notice receiver to format the notice and pass a string to the notice processor for printing. However, an application that chooses to provide its own notice receiver will typically ignore the notice processor layer and just do all the work in the notice receiver.

This function takes a new block to act as the handler, which should accept a single parameter that will be a PG::Result object, and returns the Proc object previously set, or nil if it was previously the default.

If you pass no arguments, it will reset the handler to the default.

Note: The result passed to the block should not be used outside of the block, since the corresponding C object could be freed after the block finishes.

static VALUE
pgconn_set_notice_receiver(VALUE self)
{
        VALUE proc, old_proc;
        t_pg_connection *this = pg_get_connection_safe( self );

        /* If default_notice_receiver is unset, assume that the current
         * notice receiver is the default, and save it to a global variable.
         * This should not be a problem because the default receiver is
         * always the same, so won't vary among connections.
         */
        if(default_notice_receiver == NULL)
                default_notice_receiver = PQsetNoticeReceiver(this->pgconn, NULL, NULL);

        old_proc = this->notice_receiver;
        if( rb_block_given_p() ) {
                proc = rb_block_proc();
                PQsetNoticeReceiver(this->pgconn, gvl_notice_receiver_proxy, (void *)self);
        } else {
                /* if no block is given, set back to default */
                proc = Qnil;
                PQsetNoticeReceiver(this->pgconn, default_notice_receiver, NULL);
        }

        this->notice_receiver = proc;
        return old_proc;
}
anchor
set_single_row_mode → self

To enter single-row mode, call this method immediately after a successful call of send_query (or a sibling function). This mode selection is effective only for the currently executing query. Then call Connection#get_result repeatedly, until it returns nil.

Each (but the last) received Result has exactly one row and a Result#result_status of PGRES_SINGLE_TUPLE. The last Result has zero rows and is used to indicate a successful execution of the query. All of these Result objects will contain the same row description data (column names, types, etc) that an ordinary Result object for the query would have.

Caution: While processing a query, the server may return some rows and then encounter an error, causing the query to be aborted. Ordinarily, pg discards any such rows and reports only the error. But in single-row mode, those rows will have already been returned to the application. Hence, the application will see some Result objects followed by an Error raised in get_result. For proper transactional behavior, the application must be designed to discard or undo whatever has been done with the previously-processed rows, if the query ultimately fails.

Example:

conn.send_query( "your SQL command" )
conn.set_single_row_mode
loop do
  res = conn.get_result or break
  res.check
  res.each do |row|
    # do something with the received row
  end
end
static VALUE
pgconn_set_single_row_mode(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);

        if( PQsetSingleRowMode(conn) == 0 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return self;
}
anchor
setnonblocking(Boolean) → nil

Sets the nonblocking status of the connection. In the blocking state, calls to send_query will block until the message is sent to the server, but will not wait for the query results. In the nonblocking state, calls to send_query will return an error if the socket is not ready for writing. Note: This function does not affect exec, because that function doesn’t return until the server has processed the query and returned the results.

Returns nil.

# File lib/pg/connection.rb, line 371
def setnonblocking(enabled)
        singleton_class.async_send_api = !enabled
        self.flush_data = !enabled
        sync_setnonblocking(true)
end
Also aliased as: async_setnonblocking
anchor
socket() → Integer

This method is deprecated. Please use the more portable method socket_io .

Returns the socket’s file descriptor for this connection. IO.for_fd() can be used to build a proper IO object to the socket. If you do so, you will likely also want to set autoclose=false on it to prevent Ruby from closing the socket to PostgreSQL if it goes out of scope. Alternatively, you can use socket_io, which creates an IO that’s associated with the connection object itself, and so won’t go out of scope until the connection does.

Note: On Windows the file descriptor is not usable, since it can not be used to build a Ruby IO object.

static VALUE
pgconn_socket(VALUE self)
{
        int sd;
        pg_deprecated(4, ("conn.socket is deprecated and should be replaced by conn.socket_io"));

        if( (sd = PQsocket(pg_get_pgconn(self))) < 0)
                pg_raise_conn_error( rb_eConnectionBad, self, "PQsocket() can't get socket descriptor");

        return INT2NUM(sd);
}
anchor
socket_io() → IO

Fetch an IO object created from the Connection’s underlying socket. This object can be used per socket_io.wait_readable, socket_io.wait_writable or for IO.select to wait for events while running asynchronous API calls. IO#wait_*able is is Fiber.scheduler compatible in contrast to IO.select.

The IO object can change while the connection is established, but is memorized afterwards. So be sure not to cache the IO object, but repeat calling conn.socket_io instead.

Using this method also works on Windows in contrast to using socket . It also avoids the problem of the underlying connection being closed by Ruby when an IO created using IO.for_fd(conn.socket) goes out of scope.

static VALUE
pgconn_socket_io(VALUE self)
{
        int sd;
        int ruby_sd;
        t_pg_connection *this = pg_get_connection_safe( self );
        VALUE cSocket;
        VALUE socket_io = this->socket_io;

        if ( !RTEST(socket_io) ) {
                if( (sd = PQsocket(this->pgconn)) < 0){
                        pg_raise_conn_error( rb_eConnectionBad, self, "PQsocket() can't get socket descriptor");
                }

                #ifdef _WIN32
                        ruby_sd = rb_w32_wrap_io_handle((HANDLE)(intptr_t)sd, O_RDWR|O_BINARY|O_NOINHERIT);
                        if( ruby_sd == -1 )
                                pg_raise_conn_error( rb_eConnectionBad, self, "Could not wrap win32 socket handle");

                        this->ruby_sd = ruby_sd;
                #else
                        ruby_sd = sd;
                #endif

                cSocket = rb_const_get(rb_cObject, rb_intern("BasicSocket"));
                socket_io = rb_funcall( cSocket, rb_intern("for_fd"), 1, INT2NUM(ruby_sd));

                /* Disable autoclose feature */
                rb_funcall( socket_io, s_id_autoclose_set, 1, Qfalse );

                this->socket_io = socket_io;
        }

        return socket_io;
}
anchor
ssl_attribute(attribute_name) → String

Returns SSL-related information about the connection.

The list of available attributes varies depending on the SSL library being used, and the type of connection. If an attribute is not available, returns nil.

The following attributes are commonly available:

library

Name of the SSL implementation in use. (Currently, only “OpenSSL” is implemented)

protocol

SSL/TLS version in use. Common values are “SSLv2”, “SSLv3”, “TLSv1”, “TLSv1.1” and “TLSv1.2”, but an implementation may return other strings if some other protocol is used.

key_bits

Number of key bits used by the encryption algorithm.

cipher

A short name of the ciphersuite used, e.g. “DHE-RSA-DES-CBC3-SHA”. The names are specific to each SSL implementation.

compression

If SSL compression is in use, returns the name of the compression algorithm, or “on” if compression is used but the algorithm is not known. If compression is not in use, returns “off”.

See also ssl_attribute_names and the corresponding libpq function.

Available since PostgreSQL-9.5

static VALUE
pgconn_ssl_attribute(VALUE self, VALUE attribute_name)
{
        const char *p_attr;

        p_attr = PQsslAttribute(pg_get_pgconn(self), StringValueCStr(attribute_name));
        return p_attr ? rb_str_new_cstr(p_attr) : Qnil;
}
anchor
ssl_attribute_names → Array

Return an array of SSL attribute names available.

See also ssl_attribute

Available since PostgreSQL-9.5

static VALUE
pgconn_ssl_attribute_names(VALUE self)
{
        int i;
        const char * const * p_list = PQsslAttributeNames(pg_get_pgconn(self));
        VALUE ary = rb_ary_new();

        for ( i = 0; p_list[i]; i++ ) {
                rb_ary_push( ary, rb_str_new_cstr( p_list[i] ));
        }
        return ary;
}
anchor
ssl_attributes → Hash

Returns SSL-related information about the connection as key/value pairs

The available attributes varies depending on the SSL library being used, and the type of connection.

See also ssl_attribute

# File lib/pg/connection.rb, line 293
def ssl_attributes
        ssl_attribute_names.each.with_object({}) do |n,h|
                h[n] = ssl_attribute(n)
        end
end
anchor
ssl_in_use? → Boolean

Returns true if the connection uses SSL/TLS, false if not.

Available since PostgreSQL-9.5

static VALUE
pgconn_ssl_in_use(VALUE self)
{
        return PQsslInUse(pg_get_pgconn(self)) ? Qtrue : Qfalse;
}
anchor
status()

Returns the status of the connection, which is one:

PG::Constants::CONNECTION_OK
PG::Constants::CONNECTION_BAD

… and other constants of kind PG::Constants::CONNECTION_*

Example:

PG.constants.grep(/CONNECTION_/).find{|c| PG.const_get(c) == conn.status} # => :CONNECTION_OK
static VALUE
pgconn_status(VALUE self)
{
        return INT2NUM(PQstatus(pg_get_pgconn(self)));
}
anchor
sync_cancel()
static VALUE
pgconn_sync_cancel(VALUE self)
{
        char errbuf[256];
        PGcancel *cancel;
        VALUE retval;
        int ret;

        cancel = PQgetCancel(pg_get_pgconn(self));
        if(cancel == NULL)
                pg_raise_conn_error( rb_ePGerror, self, "Invalid connection!");

        ret = gvl_PQcancel(cancel, errbuf, sizeof(errbuf));
        if(ret == 1)
                retval = Qnil;
        else
                retval = rb_str_new2(errbuf);

        PQfreeCancel(cancel);
        return retval;
}
anchor
sync_describe_portal( portal_name ) → PG::Result

This function has the same behavior as async_describe_portal, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but describe_portal instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_describe_portal(self, stmt_name)
        VALUE self, stmt_name;
{
        PGresult *result;
        VALUE rb_pgresult;
        t_pg_connection *this = pg_get_connection_safe( self );
        const char *stmt;
        if(NIL_P(stmt_name)) {
                stmt = NULL;
        }
        else {
                stmt = pg_cstr_enc(stmt_name, this->enc_idx);
        }
        result = gvl_PQdescribePortal(this->pgconn, stmt);
        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);
        return rb_pgresult;
}
anchor
sync_describe_prepared( statement_name ) → PG::Result

This function has the same behavior as async_describe_prepared, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but describe_prepared instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_describe_prepared(VALUE self, VALUE stmt_name)
{
        PGresult *result;
        VALUE rb_pgresult;
        t_pg_connection *this = pg_get_connection_safe( self );
        const char *stmt;
        if(NIL_P(stmt_name)) {
                stmt = NULL;
        }
        else {
                stmt = pg_cstr_enc(stmt_name, this->enc_idx);
        }
        result = gvl_PQdescribePrepared(this->pgconn, stmt);
        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);
        return rb_pgresult;
}
anchor
sync_encrypt_password(p1, p2, p3 = v3)
static VALUE
pgconn_sync_encrypt_password(int argc, VALUE *argv, VALUE self)
{
        char *encrypted = NULL;
        VALUE rval = Qnil;
        VALUE password, username, algorithm;
        PGconn *conn = pg_get_pgconn(self);

        rb_scan_args( argc, argv, "21", &password, &username, &algorithm );

        Check_Type(password, T_STRING);
        Check_Type(username, T_STRING);

        encrypted = gvl_PQencryptPasswordConn(conn, StringValueCStr(password), StringValueCStr(username), RTEST(algorithm) ? StringValueCStr(algorithm) : NULL);
        if ( encrypted ) {
                rval = rb_str_new2( encrypted );
                PQfreemem( encrypted );
        } else {
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));
        }

        return rval;
}
anchor
sync_exec(sql) → PG::Result
sync_exec(sql) {|pg_result| block }

This function has the same behavior as async_exec, but is implemented using the synchronous command processing API of libpq. It’s not recommended to use explicit sync or async variants but exec instead, unless you have a good reason to do so.

Both sync_exec and async_exec release the GVL while waiting for server response, so that concurrent threads will get executed. However async_exec has two advantages:

  1. async_exec can be aborted by signals (like Ctrl-C), while exec blocks signal processing until the query is answered.

  2. Ruby VM gets notified about IO blocked operations and can pass them through Fiber.scheduler. So only async_* methods are compatible to event based schedulers like the async gem.

static VALUE
pgconn_sync_exec(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGresult *result = NULL;
        VALUE rb_pgresult;

        /* If called with no or nil parameters, use PQexec for compatibility */
        if ( argc == 1 || (argc >= 2 && argc <= 4 && NIL_P(argv[1]) )) {
                VALUE query_str = argv[0];

                result = gvl_PQexec(this->pgconn, pg_cstr_enc(query_str, this->enc_idx));
                rb_pgresult = pg_new_result(result, self);
                pg_result_check(rb_pgresult);
                if (rb_block_given_p()) {
                        return rb_ensure(rb_yield, rb_pgresult, pg_result_clear, rb_pgresult);
                }
                return rb_pgresult;
        }
        pg_deprecated(0, ("forwarding exec to exec_params is deprecated"));

        /* Otherwise, just call #exec_params instead for backward-compatibility */
        return pgconn_sync_exec_params( argc, argv, self );

}
anchor
sync_exec_params(sql, params[, result_format[, type_map]] ) → PG::Result
sync_exec_params(sql, params[, result_format[, type_map]] ) {|pg_result| block }

This function has the same behavior as async_exec_params, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but exec_params instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_exec_params( int argc, VALUE *argv, VALUE self )
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGresult *result = NULL;
        VALUE rb_pgresult;
        VALUE command, in_res_fmt;
        int nParams;
        int resultFormat;
        struct query_params_data paramsData = { this->enc_idx };

        /* For compatibility we accept 1 to 4 parameters */
        rb_scan_args(argc, argv, "13", &command, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 1;

        /*
         * For backward compatibility no or +nil+ for the second parameter
         * is passed to #exec
         */
        if ( NIL_P(paramsData.params) ) {
                pg_deprecated(1, ("forwarding exec_params to exec is deprecated"));
                return pgconn_sync_exec( 1, argv, self );
        }
        pgconn_query_assign_typemap( self, &paramsData );

        resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
        nParams = alloc_query_params( &paramsData );

        result = gvl_PQexecParams(this->pgconn, pg_cstr_enc(command, paramsData.enc_idx), nParams, paramsData.types,
                (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats, resultFormat);

        free_query_params( &paramsData );

        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);

        if (rb_block_given_p()) {
                return rb_ensure(rb_yield, rb_pgresult, pg_result_clear, rb_pgresult);
        }

        return rb_pgresult;
}
anchor
sync_exec_prepared(statement_name [, params, result_format[, type_map]] ) → PG::Result
sync_exec_prepared(statement_name [, params, result_format[, type_map]] ) {|pg_result| block }

This function has the same behavior as async_exec_prepared, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but exec_prepared instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_exec_prepared(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGresult *result = NULL;
        VALUE rb_pgresult;
        VALUE name, in_res_fmt;
        int nParams;
        int resultFormat;
        struct query_params_data paramsData = { this->enc_idx };

        rb_scan_args(argc, argv, "13", &name, &paramsData.params, &in_res_fmt, &paramsData.typemap);
        paramsData.with_types = 0;

        if(NIL_P(paramsData.params)) {
                paramsData.params = rb_ary_new2(0);
        }
        pgconn_query_assign_typemap( self, &paramsData );

        resultFormat = NIL_P(in_res_fmt) ? 0 : NUM2INT(in_res_fmt);
        nParams = alloc_query_params( &paramsData );

        result = gvl_PQexecPrepared(this->pgconn, pg_cstr_enc(name, paramsData.enc_idx), nParams,
                (const char * const *)paramsData.values, paramsData.lengths, paramsData.formats,
                resultFormat);

        free_query_params( &paramsData );

        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);
        if (rb_block_given_p()) {
                return rb_ensure(rb_yield, rb_pgresult,
                        pg_result_clear, rb_pgresult);
        }
        return rb_pgresult;
}
anchor
sync_flush()
static VALUE
pgconn_sync_flush(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        int ret = PQflush(conn);
        if(ret == -1)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return (ret) ? Qfalse : Qtrue;
}
anchor
sync_get_copy_data(p1 = v1, p2 = v2)
static VALUE
pgconn_sync_get_copy_data(int argc, VALUE *argv, VALUE self )
{
        VALUE async_in;
        VALUE result;
        int ret;
        char *buffer;
        VALUE decoder;
        t_pg_coder *p_coder = NULL;
        t_pg_connection *this = pg_get_connection_safe( self );

        rb_scan_args(argc, argv, "02", &async_in, &decoder);

        if( NIL_P(decoder) ){
                if( !NIL_P(this->decoder_for_get_copy_data) ){
                        p_coder = RTYPEDDATA_DATA( this->decoder_for_get_copy_data );
                }
        } else {
                /* Check argument type and use argument decoder */
                TypedData_Get_Struct(decoder, t_pg_coder, &pg_coder_type, p_coder);
        }

        ret = gvl_PQgetCopyData(this->pgconn, &buffer, RTEST(async_in));
        if(ret == -2){ /* error */
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(this->pgconn));
        }
        if(ret == -1) { /* No data left */
                return Qnil;
        }
        if(ret == 0) { /* would block */
                return Qfalse;
        }

        if( p_coder ){
                t_pg_coder_dec_func dec_func = pg_coder_dec_func( p_coder, p_coder->format );
                result =  dec_func( p_coder, buffer, ret, 0, 0, this->enc_idx );
        } else {
                result = rb_str_new(buffer, ret);
        }

        PQfreemem(buffer);
        return result;
}
anchor
sync_get_last_result( ) → PG::Result

This function has the same behavior as async_get_last_result, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but get_last_result instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_get_last_result(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        VALUE rb_pgresult = Qnil;
        PGresult *cur, *prev;


        cur = prev = NULL;
        while ((cur = gvl_PQgetResult(conn)) != NULL) {
                int status;

                if (prev) PQclear(prev);
                prev = cur;

                status = PQresultStatus(cur);
                if (status == PGRES_COPY_OUT || status == PGRES_COPY_IN || status == PGRES_COPY_BOTH)
                        break;
        }

        if (prev) {
                rb_pgresult = pg_new_result( prev, self );
                pg_result_check(rb_pgresult);
        }

        return rb_pgresult;
}
anchor
sync_get_result()
static VALUE
pgconn_sync_get_result(VALUE self)
{
        PGconn *conn = pg_get_pgconn(self);
        PGresult *result;
        VALUE rb_pgresult;

        result = gvl_PQgetResult(conn);
        if(result == NULL)
                return Qnil;
        rb_pgresult = pg_new_result(result, self);
        if (rb_block_given_p()) {
                return rb_ensure(rb_yield, rb_pgresult,
                        pg_result_clear, rb_pgresult);
        }
        return rb_pgresult;
}
anchor
sync_isnonblocking()
static VALUE
pgconn_sync_isnonblocking(VALUE self)
{
        return PQisnonblocking(pg_get_pgconn(self)) ? Qtrue : Qfalse;
}
anchor
sync_prepare(stmt_name, sql [, param_types ] ) → PG::Result

This function has the same behavior as async_prepare, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but prepare instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_prepare(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGresult *result = NULL;
        VALUE rb_pgresult;
        VALUE name, command, in_paramtypes;
        VALUE param;
        int i = 0;
        int nParams = 0;
        Oid *paramTypes = NULL;
        const char *name_cstr;
        const char *command_cstr;
        int enc_idx = this->enc_idx;

        rb_scan_args(argc, argv, "21", &name, &command, &in_paramtypes);
        name_cstr = pg_cstr_enc(name, enc_idx);
        command_cstr = pg_cstr_enc(command, enc_idx);

        if(! NIL_P(in_paramtypes)) {
                Check_Type(in_paramtypes, T_ARRAY);
                nParams = (int)RARRAY_LEN(in_paramtypes);
                paramTypes = ALLOC_N(Oid, nParams);
                for(i = 0; i < nParams; i++) {
                        param = rb_ary_entry(in_paramtypes, i);
                        if(param == Qnil)
                                paramTypes[i] = 0;
                        else
                                paramTypes[i] = NUM2UINT(param);
                }
        }
        result = gvl_PQprepare(this->pgconn, name_cstr, command_cstr, nParams, paramTypes);

        xfree(paramTypes);

        rb_pgresult = pg_new_result(result, self);
        pg_result_check(rb_pgresult);
        return rb_pgresult;
}
anchor
sync_put_copy_data(p1, p2 = v2)
static VALUE
pgconn_sync_put_copy_data(int argc, VALUE *argv, VALUE self)
{
        int ret;
        int len;
        t_pg_connection *this = pg_get_connection_safe( self );
        VALUE value;
        VALUE buffer = Qnil;
        VALUE encoder;
        VALUE intermediate;
        t_pg_coder *p_coder = NULL;

        rb_scan_args( argc, argv, "11", &value, &encoder );

        if( NIL_P(encoder) ){
                if( NIL_P(this->encoder_for_put_copy_data) ){
                        buffer = value;
                } else {
                        p_coder = RTYPEDDATA_DATA( this->encoder_for_put_copy_data );
                }
        } else {
                /* Check argument type and use argument encoder */
                TypedData_Get_Struct(encoder, t_pg_coder, &pg_coder_type, p_coder);
        }

        if( p_coder ){
                t_pg_coder_enc_func enc_func;
                int enc_idx = this->enc_idx;

                enc_func = pg_coder_enc_func( p_coder );
                len = enc_func( p_coder, value, NULL, &intermediate, enc_idx);

                if( len == -1 ){
                        /* The intermediate value is a String that can be used directly. */
                        buffer = intermediate;
                } else {
                        buffer = rb_str_new(NULL, len);
                        len = enc_func( p_coder, value, RSTRING_PTR(buffer), &intermediate, enc_idx);
                        rb_str_set_len( buffer, len );
                }
        }

        Check_Type(buffer, T_STRING);

        ret = gvl_PQputCopyData(this->pgconn, RSTRING_PTR(buffer), RSTRING_LENINT(buffer));
        if(ret == -1)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(this->pgconn));

        RB_GC_GUARD(intermediate);
        RB_GC_GUARD(buffer);

        return (ret) ? Qtrue : Qfalse;
}
anchor
sync_put_copy_end(p1 = v1)
static VALUE
pgconn_sync_put_copy_end(int argc, VALUE *argv, VALUE self)
{
        VALUE str;
        int ret;
        const char *error_message = NULL;
        t_pg_connection *this = pg_get_connection_safe( self );

        if (rb_scan_args(argc, argv, "01", &str) == 0)
                error_message = NULL;
        else
                error_message = pg_cstr_enc(str, this->enc_idx);

        ret = gvl_PQputCopyEnd(this->pgconn, error_message);
        if(ret == -1)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(this->pgconn));

        return (ret) ? Qtrue : Qfalse;
}
anchor
sync_reset()
static VALUE
pgconn_sync_reset( VALUE self )
{
        pgconn_close_socket_io( self );
        gvl_PQreset( pg_get_pgconn(self) );
        return self;
}
anchor
sync_set_client_encoding( encoding )

This function has the same behavior as async_set_client_encoding, but is implemented using the synchronous command processing API of libpq. See async_exec for the differences between the two API variants. It’s not recommended to use explicit sync or async variants but set_client_encoding instead, unless you have a good reason to do so.

static VALUE
pgconn_sync_set_client_encoding(VALUE self, VALUE str)
{
        PGconn *conn = pg_get_pgconn( self );

        Check_Type(str, T_STRING);

        if ( (gvl_PQsetClientEncoding(conn, StringValueCStr(str))) == -1 )
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        pgconn_set_internal_encoding_index( self );

        return Qnil;
}
anchor
sync_setnonblocking(p1)
static VALUE
pgconn_sync_setnonblocking(VALUE self, VALUE state)
{
        int arg;
        PGconn *conn = pg_get_pgconn(self);
        if(state == Qtrue)
                arg = 1;
        else if (state == Qfalse)
                arg = 0;
        else
                rb_raise(rb_eArgError, "Boolean value expected");

        if(PQsetnonblocking(conn, arg) == -1)
                pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));

        return Qnil;
}
anchor
trace( stream ) → nil

Enables tracing message passing between backend. The trace message will be written to the stream stream, which must implement a method fileno that returns a writable file descriptor.

static VALUE
pgconn_trace(VALUE self, VALUE stream)
{
        VALUE fileno;
        FILE *new_fp;
        int old_fd, new_fd;
        VALUE new_file;
        t_pg_connection *this = pg_get_connection_safe( self );

        if(!rb_respond_to(stream,rb_intern("fileno")))
                rb_raise(rb_eArgError, "stream does not respond to method: fileno");

        fileno = rb_funcall(stream, rb_intern("fileno"), 0);
        if(fileno == Qnil)
                rb_raise(rb_eArgError, "can't get file descriptor from stream");

        /* Duplicate the file descriptor and re-open
         * it. Then, make it into a ruby File object
         * and assign it to an instance variable.
         * This prevents a problem when the File
         * object passed to this function is closed
         * before the connection object is. */
        old_fd = NUM2INT(fileno);
        new_fd = dup(old_fd);
        new_fp = fdopen(new_fd, "w");

        if(new_fp == NULL)
                rb_raise(rb_eArgError, "stream is not writable");

        new_file = rb_funcall(rb_cIO, rb_intern("new"), 1, INT2NUM(new_fd));
        this->trace_stream = new_file;

        PQtrace(this->pgconn, new_fp);
        return Qnil;
}
anchor
transaction { |conn| ... } → result of the block

Executes a BEGIN at the start of the block, and a COMMIT at the end of the block, or ROLLBACK if any exception occurs.

# File lib/pg/connection.rb, line 236
def transaction
        rollback = false
        exec "BEGIN"
        yield(self)
rescue Exception
        rollback = true
        cancel if transaction_status == PG::PQTRANS_ACTIVE
        block
        exec "ROLLBACK"
        raise
ensure
        exec "COMMIT" unless rollback
end
anchor
transaction_status()

returns one of the following statuses:

PQTRANS_IDLE    = 0 (connection idle)
PQTRANS_ACTIVE  = 1 (command in progress)
PQTRANS_INTRANS = 2 (idle, within transaction block)
PQTRANS_INERROR = 3 (idle, within failed transaction)
PQTRANS_UNKNOWN = 4 (cannot determine status)
static VALUE
pgconn_transaction_status(VALUE self)
{
        return INT2NUM(PQtransactionStatus(pg_get_pgconn(self)));
}
anchor
tty()

Obsolete function.

static VALUE
pgconn_tty(VALUE self)
{
        return rb_str_new2("");
}
anchor
type_map_for_queries → TypeMap

Returns the default TypeMap that is currently set for type casts of query bind parameters.

static VALUE
pgconn_type_map_for_queries_get(VALUE self)
{
        t_pg_connection *this = pg_get_connection( self );

        return this->type_map_for_queries;
}
anchor
type_map_for_queries = typemap

Set the default TypeMap that is used for type casts of query bind parameters.

typemap must be a kind of PG::TypeMap .

static VALUE
pgconn_type_map_for_queries_set(VALUE self, VALUE typemap)
{
        t_pg_connection *this = pg_get_connection( self );
        t_typemap *tm;
        UNUSED(tm);

        /* Check type of method param */
        TypedData_Get_Struct(typemap, t_typemap, &pg_typemap_type, tm);

        this->type_map_for_queries = typemap;

        return typemap;
}
anchor
type_map_for_results → TypeMap

Returns the default TypeMap that is currently set for type casts of result values.

static VALUE
pgconn_type_map_for_results_get(VALUE self)
{
        t_pg_connection *this = pg_get_connection( self );

        return this->type_map_for_results;
}
anchor
type_map_for_results = typemap

Set the default TypeMap that is used for type casts of result values.

typemap must be a kind of PG::TypeMap .

static VALUE
pgconn_type_map_for_results_set(VALUE self, VALUE typemap)
{
        t_pg_connection *this = pg_get_connection( self );
        t_typemap *tm;
        UNUSED(tm);

        TypedData_Get_Struct(typemap, t_typemap, &pg_typemap_type, tm);
        this->type_map_for_results = typemap;

        return typemap;
}
anchor
PG::Connection.unescape_bytea( string )

Converts an escaped string representation of binary data into binary data — the reverse of escape_bytea. This is needed when retrieving bytea data in text format, but not when retrieving it in binary format.

static VALUE
pgconn_s_unescape_bytea(VALUE self, VALUE str)
{
        unsigned char *from, *to;
        size_t to_len;
        VALUE ret;

        UNUSED( self );

        Check_Type(str, T_STRING);
        from = (unsigned char*)StringValueCStr(str);

        to = PQunescapeBytea(from, &to_len);

        ret = rb_str_new((char*)to, to_len);
        PQfreemem(to);
        return ret;
}
Also aliased as: unescape_bytea
anchor
untrace() → nil

Disables the message tracing.

static VALUE
pgconn_untrace(VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );

        PQuntrace(this->pgconn);
        rb_funcall(this->trace_stream, rb_intern("close"), 0);
        this->trace_stream = Qnil;
        return Qnil;
}
anchor
user()

Returns the authenticated user name.

static VALUE
pgconn_user(VALUE self)
{
        char *user = PQuser(pg_get_pgconn(self));
        if (!user) return Qnil;
        return rb_str_new2(user);
}
anchor
wait_for_notify( [ timeout ] ) { |event, pid, payload| block } → String

Blocks while waiting for notification(s), or until the optional timeout is reached, whichever comes first. timeout is measured in seconds and can be fractional.

Returns nil if timeout is reached, the name of the NOTIFY event otherwise. If used in block form, passes the name of the NOTIFY event, the generating pid and the optional payload string into the block.

static VALUE
pgconn_wait_for_notify(int argc, VALUE *argv, VALUE self)
{
        t_pg_connection *this = pg_get_connection_safe( self );
        PGnotify *pnotification;
        struct timeval timeout;
        struct timeval *ptimeout = NULL;
        VALUE timeout_in = Qnil, relname = Qnil, be_pid = Qnil, extra = Qnil;
        double timeout_sec;

        rb_scan_args( argc, argv, "01", &timeout_in );

        if ( RTEST(timeout_in) ) {
                timeout_sec = NUM2DBL( timeout_in );
                timeout.tv_sec = (time_t)timeout_sec;
                timeout.tv_usec = (suseconds_t)( (timeout_sec - (long)timeout_sec) * 1e6 );
                ptimeout = &timeout;
        }

        pnotification = (PGnotify*) wait_socket_readable( self, ptimeout, notify_readable);

        /* Return nil if the select timed out */
        if ( !pnotification ) return Qnil;

        relname = rb_str_new2( pnotification->relname );
        PG_ENCODING_SET_NOCHECK( relname, this->enc_idx );
        be_pid = INT2NUM( pnotification->be_pid );
        if ( *pnotification->extra ) {
                extra = rb_str_new2( pnotification->extra );
                PG_ENCODING_SET_NOCHECK( extra, this->enc_idx );
        }
        PQfreemem( pnotification );

        if ( rb_block_given_p() )
                rb_yield_values( 3, relname, be_pid, extra );

        return relname;
}
Also aliased as: notifies_wait