Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

### Home Classes Methods

### In Files

- lib/active_record/connection_adapters/postgresql_adapter.rb

### Parent

AbstractAdapter

### Methods

- ::new
- #active?
- #adapter_name
- #add_column
- #begin_db_transaction
- #change_column
- #change_column_default
- #change_column_null
- #client_min_messages
- #client_min_messages=
- #columns
- #commit_db_transaction
- #create
- #create_database
- #create_savepoint
- #current_database
- #disconnect!
- #encoding
- #escape_bytea
- #execute
- #index_name_length
- #indexes
- #insert
- #outside_transaction?
- #postgresql_version
- #primary_key
- #quote_table_name
- #reconnect!
- #release_savepoint
- #rename_column
- #rename_table
- #rollback_db_transaction
- #rollback_to_savepoint
- #schema_search_path
- #schema_search_path=
- #select_rows
- #set_standard_conforming_strings
- #supports_ddl_transactions?
- #supports_insert_with_returning?
- #supports_migrations?
- #supports_savepoints?
- #table_alias_length
- #table_exists?
- #tables
- #translate_exception
- #type_to_sql
- #unescape_bytea
- #update_sql

### Files

- README.rdoc

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No matching classes.

# ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

The PostgreSQL adapter works both with the native C (ruby.scripting.ca/postgres/) and the pure Ruby (available both as gem and from rubyforge.org/frs/?group_id=234&release_id=1944) drivers.

Options:

- `:host` - Defaults to "localhost".

- `:port` - Defaults to 5432.

- `:username` - Defaults to nothing.

- `:password` - Defaults to nothing.

- `:database` - The name of the database. No default, must be provided.

- `:schema_search_path` - An optional schema search path for the connection given as a string of comma-separated schema names. This is backward-compatible with the `:schema_order` option.

- `:encoding` - An optional client encoding that is used in a `SET client_encoding TO <encoding>` call on the connection.

- `:min_messages` - An optional client min messages that is used in a `SET client_min_messages TO <min_messages>` call on the connection.

- `:allow_concurrency` - If true, use async query methods so Ruby threads don't deadlock; otherwise, use blocking query methods.

### Constants

ADAPTER_NAME
NATIVE_DATABASE_TYPES

### Public Class Methods

new(connection, logger, connection_parameters, config) click to toggle source

Initializes and connects a PostgreSQL adapter.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 219
    def initialize(connection, logger, connection_parameters, config)
      super(connection, logger)
      @connection_parameters, @config = connection_parameters, config

      # @local_tz is initialized as nil to avoid warnings when connect tries to use it
      @local_tz = nil
      @table_alias_length = nil
      @postgresql_version = nil

      connect
      @local_tz = execute('SHOW TIME ZONE').first["TimeZone"]
    end

### Public Instance Methods

active?() click to toggle source

Is this connection alive and ready for queries?

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 233
    def active?
      if @connection.respond_to?(:status)
        @connection.status == PGconn::CONNECTION_OK
      else
        # We're asking the driver, not Active Record, so use @connection.query instead of #query
        @connection.query 'SELECT 1'
        true
      end
    # postgres-pr raises a NoMethodError when querying if no connection is available.
    rescue PGError, NoMethodError
      false
    end

adapter_name() click to toggle source

Returns ‘PostgreSQL’ as adapter name for identification purposes.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 214
    def adapter_name
      ADAPTER_NAME
    end

add_column(table_name, column_name, type, options = {}) click to toggle source

Adds a new column to the named table. See TableDefinition#column for details of the options you can use.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 792
    def add_column(table_name, column_name, type, options = {})
      default = options[:default]
      notnull = options[:null] == false

      # Add the column.
      execute("ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}")

      change_column_default(table_name, column_name, default) if options_include_default?(options)
      change_column_null(table_name, column_name, false, default) if notnull
    end

begin_db_transaction() click to toggle source

Begins a transaction.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 508
    def begin_db_transaction
      execute "BEGIN"
    end

change_column(table_name, column_name, type, options = {}) click to toggle source

Changes the column of a table.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 804
    def change_column(table_name, column_name, type, options = {})
      quoted_table_name = quote_table_name(table_name)

      begin
        execute "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
      rescue ActiveRecord::StatementInvalid => e
        raise e if postgresql_version > 80000
        # This is PostgreSQL 7.x, so we have to use a more arcane way of doing it.
        begin
          begin_db_transaction
          tmp_column_name = "#{column_name}_ar_tmp"
          add_column(table_name, tmp_column_name, type, options)
          execute "UPDATE #{quoted_table_name} SET #{quote_column_name(tmp_column_name)} = CAST(#{quote_column_name(column_name)} AS #{type_to_sql(type, options[:limit], options[:precision], options[:scale])})"
          remove_column(table_name, column_name)
          rename_column(table_name, tmp_column_name, column_name)
          commit_db_transaction
        rescue
          rollback_db_transaction
        end
      end

      change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
      change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
    end

change_column_default(table_name, column_name, default) click to toggle source

Changes the default value of a table column.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 830
    def change_column_default(table_name, column_name, default)
      execute "ALTER TABLE #{quote_table_name(table_name)} ALTER COLUMN #{quote_column_name(column_name)} SET DEFAULT #{quote(default)}"
    end

change_column_null(table_name, column_name, null, default = nil) click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 834
    def change_column_null(table_name, column_name, null, default = nil)
      unless null || default.nil?
        execute("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
      end
      execute("ALTER TABLE #{quote_table_name(table_name)} ALTER #{quote_column_name(column_name)} #{null ? 'DROP' : 'SET'} NOT NULL")
    end

client_min_messages() click to toggle source

Returns the current client message level.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 695
    def client_min_messages
      query('SHOW client_min_messages')[0][0]
    end

client_min_messages=(level) click to toggle source

Set the client message level.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 700
    def client_min_messages=(level)
      execute("SET client_min_messages TO '#{level}'")
    end

columns(table_name, name = nil) click to toggle source

Returns the list of all column definitions for a table.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 657
    def columns(table_name, name = nil)
      # Limit, precision, and scale are all handled by the superclass.
      column_definitions(table_name).collect do |name, type, default, notnull|
        PostgreSQLColumn.new(name, default, type, notnull == 'f')
      end
    end

commit_db_transaction() click to toggle source

Commits a transaction.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 513
    def commit_db_transaction
      execute "COMMIT"
    end

create(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) click to toggle source
Alias for: insert
create_database(name, options = {}) click to toggle source

Create a new PostgreSQL database. Options include `:owner`, `:template`, `:encoding`, `:tablespace`, and `:connection_limit` (note that MySQL uses `:charset` while PostgreSQL uses `:encoding`).

Example:

    create_database config[:database], config
    create_database 'foo_development', :encoding => 'unicode'

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 552
    def create_database(name, options = {})
      options = options.reverse_merge(:encoding => "utf8")

      option_string = options.symbolize_keys.sum do |key, value|
        case key
        when :owner
          " OWNER = \"#{value}\""
        when :template
          " TEMPLATE = \"#{value}\""
        when :encoding
          " ENCODING = '#{value}'"
        when :tablespace
          " TABLESPACE = \"#{value}\""
        when :connection_limit
          " CONNECTION LIMIT = #{value}"
        else
          ""
        end
      end

      execute "CREATE DATABASE #{quote_table_name(name)}#{option_string}"
    end

create_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 526
    def create_savepoint
      execute("SAVEPOINT #{current_savepoint_name}")
    end

current_database() click to toggle source

Returns the current database name.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 665
    def current_database
      query('select current_database()')[0][0]
    end

disconnect!() click to toggle source

Close the connection.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 258
    def disconnect!
      @connection.close rescue nil
    end

encoding() click to toggle source

Returns the current database encoding format.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 670
    def encoding
      query(          SELECT pg_encoding_to_char(pg_database.encoding) FROM pg_database          WHERE pg_database.datname LIKE '#{current_database}')[0][0]
    end

escape_bytea(value) click to toggle source

Escapes binary strings for bytea input to the database.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 305
    def escape_bytea(value)
      @connection.escape_bytea(value) if value
    end

execute(sql, name = nil) click to toggle source

Executes an SQL statement, returning a PGresult object on success or raising a PGError exception otherwise.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 492
    def execute(sql, name = nil)
      log(sql, name) do
        if @async
          @connection.async_exec(sql)
        else
          @connection.exec(sql)
        end
      end
    end

index_name_length() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 850
    def index_name_length
      63
    end

indexes(table_name, name = nil) click to toggle source

Returns the list of all indexes for a table.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 623
    def indexes(table_name, name = nil)
       schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
       result = query(           SELECT distinct i.relname, d.indisunique, d.indkey, t.oid             FROM pg_class t, pg_class i, pg_index d           WHERE i.relkind = 'i'             AND d.indexrelid = i.oid             AND d.indisprimary = 'f'             AND t.oid = d.indrelid             AND t.relname = '#{table_name}'             AND i.relnamespace IN (SELECT oid FROM pg_namespace WHERE nspname IN (#{schemas}) )          ORDER BY i.relname, name)

      result.map do |row|
        index_name = row[0]
        unique = row[1] == 't'
        indkey = row[2].split(" ")
        oid = row[3]

        columns = Hash[query(          SELECT a.attnum, a.attname          FROM pg_attribute a          WHERE a.attrelid = #{oid}          AND a.attnum IN (#{indkey.join(",")}), "Columns for index #{row[0]} on #{table_name}")]

        column_names = columns.values_at(*indkey).compact
        column_names.empty? ? nil : IndexDefinition.new(table_name, index_name, unique, column_names)
      end.compact
    end

insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) click to toggle source

Executes an INSERT query and returns the new record’s ID

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 404
    def insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil)
      # Extract the table from the insert sql. Yuck.
      table = sql.split(" ", 4)[2].gsub('"', '')

      # Try an insert with 'returning id' if available (PG >= 8.2)
      if supports_insert_with_returning?
        pk, sequence_name = *pk_and_sequence_for(table) unless pk
        if pk
          id = select_value("#{sql} RETURNING #{quote_column_name(pk)}")
          clear_query_cache
          return id
        end
      end

      # Otherwise, insert then grab last_insert_id.
      if insert_id = super
        insert_id
      else
        # If neither pk nor sequence name is given, look them up.
        unless pk || sequence_name
          pk, sequence_name = *pk_and_sequence_for(table)
        end

        # If a pk is given, fallback to default sequence name.
        # Don't fetch last insert id for a table without a pk.
        if pk && sequence_name ||= default_sequence_name(table, pk)
          last_insert_id(table, sequence_name)
        end
      end
    end

Also aliased as: create
outside_transaction?() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 522
    def outside_transaction?
      @connection.transaction_status == PGconn::PQTRANS_IDLE
    end

primary_key(table) click to toggle source

Returns just a table’s primary key

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 780
    def primary_key(table)
      pk_and_sequence = pk_and_sequence_for(table)
      pk_and_sequence && pk_and_sequence.first
    end

quote_table_name(name) click to toggle source

Checks the following cases:

- table_name

- “table.name”

- schema_name.table_name

- schema_name.“table.name”

- “schema.name”.table_name

- “schema.name”.“table.name”

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 352
    def quote_table_name(name)
      schema, name_part = extract_pg_identifier_from_name(name.to_s)

      unless name_part
        quote_column_name(schema)
      else
        table_name, name_part = extract_pg_identifier_from_name(name_part)
        "#{quote_column_name(schema)}.#{quote_column_name(table_name)}"
      end
    end

reconnect!() click to toggle source

Close then reopen the connection.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 247
    def reconnect!
      if @connection.respond_to?(:reset)
        @connection.reset
        configure_connection
      else
        disconnect!
        connect
      end
    end

release_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 534
    def release_savepoint
      execute("RELEASE SAVEPOINT #{current_savepoint_name}")
    end

rename_column(table_name, column_name, new_column_name) click to toggle source

Renames a column in a table.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 842
    def rename_column(table_name, column_name, new_column_name)
      execute "ALTER TABLE #{quote_table_name(table_name)} RENAME COLUMN #{quote_column_name(column_name)} TO #{quote_column_name(new_column_name)}"
    end

rename_table(name, new_name) click to toggle source

Renames a table.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 786
    def rename_table(name, new_name)
      execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
    end

rollback_db_transaction() click to toggle source

Aborts a transaction.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 518
    def rollback_db_transaction
      execute "ROLLBACK"
    end

rollback_to_savepoint() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 530
    def rollback_to_savepoint
      execute("ROLLBACK TO SAVEPOINT #{current_savepoint_name}")
    end

schema_search_path() click to toggle source

Returns the active schema search path.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 690
    def schema_search_path
      @schema_search_path ||= query('SHOW search_path')[0][0]
    end

schema_search_path=(schema_csv) click to toggle source

Sets the schema search path to a string of comma-separated schema names. Names beginning with $ have to be quoted (e.g. $user => ‘$user’). See: www.postgresql.org/docs/current/static/ddl-schemas.html

This should be not be called manually but set in database.yml.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 682
    def schema_search_path=(schema_csv)
      if schema_csv
        execute "SET search_path TO #{schema_csv}"
        @schema_search_path = schema_csv
      end
    end

select_rows(sql, name = nil) click to toggle source

Executes a SELECT query and returns an array of rows. Each row is an array of field values.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 399
    def select_rows(sql, name = nil)
      select_raw(sql, name).last
    end

set_standard_conforming_strings() click to toggle source

Enable standard-conforming strings if available.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 277
    def set_standard_conforming_strings
      old, self.client_min_messages = client_min_messages, 'panic'
      execute('SET standard_conforming_strings = on') rescue nil
    ensure
      self.client_min_messages = old
    end

supports_ddl_transactions?() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 288
    def supports_ddl_transactions?
      true
    end

supports_insert_with_returning?() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 284
    def supports_insert_with_returning?
      postgresql_version >= 80200
    end

supports_migrations?() click to toggle source

Does PostgreSQL support migrations?

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 267
    def supports_migrations?
      true
    end

supports_savepoints?() click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 292
    def supports_savepoints?
      true
    end

table_alias_length() click to toggle source

Returns the configured supported identifier length supported by PostgreSQL, or report the default of 63 on PostgreSQL 7.x.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 298
    def table_alias_length
      @table_alias_length ||= (postgresql_version >= 80000 ? query('SHOW max_identifier_length')[0][0].to_i : 63)
    end

table_exists?(name) click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 600
    def table_exists?(name)
      name          = name.to_s
      schema, table = name.split('.', 2)

      unless table # A table was provided without a schema
        table  = schema
        schema = nil
      end

      if name =~ /^"/ # Handle quoted table names
        table  = name
        schema = nil
      end

      query(            SELECT COUNT(*)            FROM pg_tables            WHERE tablename = '#{table.gsub(/(^"|"$)/,'')}'            #{schema ? "AND schemaname = '#{schema}'" : ''}).first[0].to_i > 0
    end

tables(name = nil) click to toggle source

Returns the list of all tables in the schema search path or a specified schema.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 592
    def tables(name = nil)
      query(          SELECT tablename          FROM pg_tables          WHERE schemaname = ANY (current_schemas(false)), name).map { |row| row[0] }
    end

type_to_sql(type, limit = nil, precision = nil, scale = nil) click to toggle source

Maps logical Rails types to PostgreSQL-specific data types.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 855
    def type_to_sql(type, limit = nil, precision = nil, scale = nil)
      return super unless type.to_s == 'integer'
      return 'integer' unless limit

      case limit
        when 1, 2; 'smallint'
        when 3, 4; 'integer'
        when 5..8; 'bigint'
        else raise(ActiveRecordError, "No integer type has byte size #{limit}. Use a numeric with precision 0 instead.")
      end
    end

unescape_bytea(value) click to toggle source

Unescapes bytea output from a database to the binary string it represents. NOTE: This is NOT an inverse of escape_bytea! This is only to be used

    on escaped binary output from database drive.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 312
    def unescape_bytea(value)
      @connection.unescape_bytea(value) if value
    end

update_sql(sql, name = nil) click to toggle source

Executes an UPDATE query and returns the number of affected tuples.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 503
    def update_sql(sql, name = nil)
      super.cmd_tuples
    end

### Protected Instance Methods

postgresql_version() click to toggle source

Returns the version of the connected PostgreSQL version.

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 890
    def postgresql_version
      @postgresql_version ||=
        if @connection.respond_to?(:server_version)
          @connection.server_version
        else
          # Mimic PGconn.server_version behavior
          begin
            if query('SELECT version()')[0][0] =~ /PostgreSQL ([0-9.]+)/
              major, minor, tiny = $1.split(".")
              (major.to_i * 10000) + (minor.to_i * 100) + tiny.to_i
            else
              0
            end
          rescue
            0
          end
        end
    end

translate_exception(exception, message) click to toggle source

    # File lib/active_record/connection_adapters/postgresql_adapter.rb, line 909
    def translate_exception(exception, message)
      case exception.message
      when /duplicate key value violates unique constraint/
        RecordNotUnique.new(message, exception)
      when /violates foreign key constraint/
        InvalidForeignKey.new(message, exception)
      else
        super
      end
    end

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