Class: ActiveRecord::ConnectionAdapters::PostgreSQLAdapter

Inherits:
AbstractAdapter
  • Object
show all
Defined in:
lib/active_record/connection_adapters/postgresql_adapter.rb

Overview

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.

Instance Method Summary collapse

Methods inherited from AbstractAdapter

#log_info, #prefetch_primary_key?, #quote_table_name, #raw_connection, #requires_reloading?, #reset_runtime, #supports_count_distinct?, #verify!

Methods included from QueryCache

#cache, #uncached

Methods included from Quoting

#quote_table_name, #quoted_false, #quoted_string_prefix, #quoted_true

Methods included from DatabaseStatements

#add_limit!, #add_limit_offset!, #add_lock!, #delete, #empty_insert_statement, #insert_fixture, #reset_sequence!, #sanitize_limit, #select_all, #select_one, #select_value, #select_values, #transaction, #update

Methods included from SchemaStatements

#add_column_options!, #add_index, #add_timestamps, #assume_migrated_upto_version, #change_table, #create_table, #drop_table, #dump_schema_information, #index_name, #initialize_schema_migrations_table, #remove_column, #remove_timestamps, #structure_dump, #table_alias_for, #table_exists?

Constructor Details

#initialize(connection, logger, connection_parameters, config) ⇒ PostgreSQLAdapter

Initializes and connects a PostgreSQL adapter.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 255

def initialize(connection, logger, connection_parameters, config)
  super(connection, logger)
  @connection_parameters, @config = connection_parameters, config

  connect
end

Instance Method Details

#active? ⇒ Boolean

Is this connection alive and ready for queries?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 263

def active?
  if @connection.respond_to?(:status)
    @connection.status == PGconn::CONNECTION_OK
  else
    # We're asking the driver, not ActiveRecord, 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 ⇒ Object

Returns ‘PostgreSQL’ as adapter name for identification purposes.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 250

def adapter_name
  'PostgreSQL'
end

#add_column(table_name, column_name, type, options = {}) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 730

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

#add_order_by_for_association_limiting!(sql, options) ⇒ Object

Returns an ORDER BY clause for the passed order option.

PostgreSQL does not allow arbitrary ordering when using DISTINCT ON, so we work around this by wrapping the sql string as a sub-select and ordering in that query.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 826

def add_order_by_for_association_limiting!(sql, options) #:nodoc:
  return sql if options[:order].blank?
  
  order = options[:order].split(',').collect { |s| s.strip }.reject(&:blank?)
  order.map! { |s| 'DESC' if s =~ /\bdesc$/i }
  order = order.zip((0...order.size).to_a).map { |s,i| "id_list.alias_#{i} #{s}" }.join(', ')
  
  sql.replace "SELECT * FROM (#{sql}) AS id_list ORDER BY #{order}"
end

#begin_db_transaction ⇒ Object

Begins a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 499

def begin_db_transaction
  execute "BEGIN"
end

#change_column(table_name, column_name, type, options = {}) ⇒ Object

Changes the column of a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 742

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) ⇒ Object

Changes the default value of a table column.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 768

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) ⇒ Object 



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 772

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 ⇒ Object

Returns the current client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 639

def client_min_messages
  query('SHOW client_min_messages')[0][0]
end

#client_min_messages=(level) ⇒ Object

Set the client message level.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 644

def client_min_messages=(level)
  execute("SET client_min_messages TO '#{level}'")
end

#columns(table_name, name = nil) ⇒ Object

Returns the list of all column definitions for a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 614

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 ⇒ Object

Commits a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 504

def commit_db_transaction
  execute "COMMIT"
end

#create_database(name, options = {}) ⇒ Object

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'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 527

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

#default_sequence_name(table_name, pk = nil) ⇒ Object

Returns the sequence name for a table’s primary key or some other specified key.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 649

def default_sequence_name(table_name, pk = nil) #:nodoc:
  default_pk, default_seq = pk_and_sequence_for(table_name)
  default_seq || "#{table_name}_#{pk || default_pk || 'id'}_seq"
end

#disable_referential_integrity(&block) ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 405

def disable_referential_integrity(&block) #:nodoc:
  if supports_disable_referential_integrity?() then
    execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
  end
  yield
ensure
  if supports_disable_referential_integrity?() then
    execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
  end
end

#disconnect! ⇒ Object

Close the connection.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 288

def disconnect!
  @connection.close rescue nil
end

#distinct(columns, order_by) ⇒ Object

Returns a SELECT DISTINCT clause for a given set of columns and a given ORDER BY clause.

PostgreSQL requires the ORDER BY columns in the select list for distinct queries, and requires that the ORDER BY include the distinct column.

distinct("posts.id", "posts.created_at desc")



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 807

def distinct(columns, order_by) #:nodoc:
  return "DISTINCT #{columns}" if order_by.blank?

  # Construct a clean list of column names from the ORDER BY clause, removing
  # any ASC/DESC modifiers
  order_columns = order_by.split(',').collect { |s| s.split.first }
  order_columns.delete_if &:blank?
  order_columns = order_columns.zip((0...order_columns.size).to_a).map { |s,i| "#{s} AS alias_#{i}" }

  # Return a DISTINCT ON() clause that's distinct on the columns we want but includes
  # all the required columns for the ORDER BY to work properly.
  sql = "DISTINCT ON (#{columns}) #{columns}, "
  sql << order_columns * ', '
end

#drop_database(name) ⇒ Object

Drops a PostgreSQL database

Example:

drop_database 'matt_development'



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 554

def drop_database(name) #:nodoc:
  if postgresql_version >= 80200
    execute "DROP DATABASE IF EXISTS #{quote_table_name(name)}"
  else
    begin
      execute "DROP DATABASE #{quote_table_name(name)}"
    rescue ActiveRecord::StatementInvalid
      @logger.warn "#{name} database doesn't exist." if @logger
    end
  end
end

#execute(sql, name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 483

def execute(sql, name = nil)
  log(sql, name) do
    if @async
      @connection.async_exec(sql)
    else
      @connection.exec(sql)
    end
  end
end

#indexes(table_name, name = nil) ⇒ Object

Returns the list of all indexes for a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 578

def indexes(table_name, name = nil)
   schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
   result = query(<<-SQL, name)
     SELECT distinct i.relname, d.indisunique, a.attname
       FROM pg_class t, pg_class i, pg_index d, pg_attribute a
     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}) )
       AND a.attrelid = t.oid
       AND ( d.indkey[0]=a.attnum OR d.indkey[1]=a.attnum
          OR d.indkey[2]=a.attnum OR d.indkey[3]=a.attnum
          OR d.indkey[4]=a.attnum OR d.indkey[5]=a.attnum
          OR d.indkey[6]=a.attnum OR d.indkey[7]=a.attnum
          OR d.indkey[8]=a.attnum OR d.indkey[9]=a.attnum )
    ORDER BY i.relname
  SQL

  current_index = nil
  indexes = []

  result.each do |row|
    if current_index != row[0]
      indexes << IndexDefinition.new(table_name, row[0], row[1] == "t", [])
      current_index = row[0]
    end

    indexes.last.columns << row[2]
  end

  indexes
end

#insert(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 425

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

#native_database_types ⇒ Object

:nodoc:



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 292

def native_database_types #:nodoc:
  {
    :primary_key => "serial primary key",
    :string      => { :name => "character varying", :limit => 255 },
    :text        => { :name => "text" },
    :integer     => { :name => "integer" },
    :float       => { :name => "float" },
    :decimal     => { :name => "decimal" },
    :datetime    => { :name => "timestamp" },
    :timestamp   => { :name => "timestamp" },
    :time        => { :name => "time" },
    :date        => { :name => "date" },
    :binary      => { :name => "bytea" },
    :boolean     => { :name => "boolean" }
  }
end

#pk_and_sequence_for(table) ⇒ Object

Returns a table’s primary key and belonging sequence.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 675

def pk_and_sequence_for(table) #:nodoc:
  # First try looking for a sequence with a dependency on the
  # given table's primary key.
  result = query(<<-end_sql, 'PK and serial sequence')[0]
    SELECT attr.attname, seq.relname
    FROM pg_class      seq,
         pg_attribute  attr,
         pg_depend     dep,
         pg_namespace  name,
         pg_constraint cons
    WHERE seq.oid           = dep.objid
      AND seq.relkind       = 'S'
      AND attr.attrelid     = dep.refobjid
      AND attr.attnum       = dep.refobjsubid
      AND attr.attrelid     = cons.conrelid
      AND attr.attnum       = cons.conkey[1]
      AND cons.contype      = 'p'
      AND dep.refobjid      = '#{table}'::regclass
  end_sql

  if result.nil? or result.empty?
    # If that fails, try parsing the primary key's default value.
    # Support the 7.x and 8.0 nextval('foo'::text) as well as
    # the 8.1+ nextval('foo'::regclass).
    result = query(<<-end_sql, 'PK and custom sequence')[0]
      SELECT attr.attname,
        CASE
          WHEN split_part(def.adsrc, '''', 2) ~ '.' THEN
            substr(split_part(def.adsrc, '''', 2),
                   strpos(split_part(def.adsrc, '''', 2), '.')+1)
          ELSE split_part(def.adsrc, '''', 2)
        END
      FROM pg_class       t
      JOIN pg_attribute   attr ON (t.oid = attrelid)
      JOIN pg_attrdef     def  ON (adrelid = attrelid AND adnum = attnum)
      JOIN pg_constraint  cons ON (conrelid = adrelid AND adnum = conkey[1])
      WHERE t.oid = '#{table}'::regclass
        AND cons.contype = 'p'
        AND def.adsrc ~* 'nextval'
    end_sql
  end

  # [primary_key, sequence]
  [result.first, result.last]
rescue
  nil
end

#query(sql, name = nil) ⇒ Object

Queries the database and returns the results in an Array-like object



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 470

def query(sql, name = nil) #:nodoc:
  log(sql, name) do
    if @async
      res = @connection.async_exec(sql)
    else
      res = @connection.exec(sql)
    end
    return result_as_array(res)
  end
end

#quote(value, column = nil) ⇒ Object

Quotes PostgreSQL-specific data types for SQL input.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 343

def quote(value, column = nil) #:nodoc:
  if value.kind_of?(String) && column && column.type == :binary
    "#{quoted_string_prefix}'#{column.class.string_to_binary(value)}'"
  elsif value.kind_of?(String) && column && column.sql_type =~ /^xml$/
    "xml '#{quote_string(value)}'"
  elsif value.kind_of?(Numeric) && column && column.sql_type =~ /^money$/
    # Not truly string input, so doesn't require (or allow) escape string syntax.
    "'#{value.to_s}'"
  elsif value.kind_of?(String) && column && column.sql_type =~ /^bit/
    case value
      when /^[01]*$/
        "B'#{value}'" # Bit-string notation
      when /^[0-9A-F]*$/i
        "X'#{value}'" # Hexadecimal notation
    end
  else
    super
  end
end

#quote_column_name(name) ⇒ Object

Quotes column names for use in SQL queries.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 382

def quote_column_name(name) #:nodoc:
  %("#{name}")
end

#quote_string(s) ⇒ Object

Quotes strings for use in SQL input in the postgres driver for better performance.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 364

def quote_string(s) #:nodoc:
  if PGconn.respond_to?(:escape)
    self.class.instance_eval do
      define_method(:quote_string) do |s|
        PGconn.escape(s)
      end
    end
  else
    # There are some incorrectly compiled postgres drivers out there
    # that don't define PGconn.escape.
    self.class.instance_eval do
      remove_method(:quote_string)
    end
  end
  quote_string(s)
end

#quoted_date(value) ⇒ Object

Quote date/time values for use in SQL input. Includes microseconds if the value is a Time responding to usec.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 388

def quoted_date(value) #:nodoc:
  if value.acts_like?(:time) && value.respond_to?(:usec)
    "#{super}.#{sprintf("%06d", value.usec)}"
  else
    super
  end
end

#reconnect! ⇒ Object

Close then reopen the connection.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 277

def reconnect!
  if @connection.respond_to?(:reset)
    @connection.reset
    configure_connection
  else
    disconnect!
    connect
  end
end

#recreate_database(name) ⇒ Object

SCHEMA STATEMENTS ========================================



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 515

def recreate_database(name) #:nodoc:
  drop_database(name)
  create_database(name)
end

#remove_index(table_name, options = {}) ⇒ Object

Drops an index from a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 785

def remove_index(table_name, options = {})
  execute "DROP INDEX #{index_name(table_name, options)}"
end

#rename_column(table_name, column_name, new_column_name) ⇒ Object

Renames a column in a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 780

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) ⇒ Object

Renames a table.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 724

def rename_table(name, new_name)
  execute "ALTER TABLE #{quote_table_name(name)} RENAME TO #{quote_table_name(new_name)}"
end

#reset_pk_sequence!(table, pk = nil, sequence = nil) ⇒ Object

Resets the sequence of a table’s primary key to the maximum value.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 655

def reset_pk_sequence!(table, pk = nil, sequence = nil) #:nodoc:
  unless pk and sequence
    default_pk, default_sequence = pk_and_sequence_for(table)
    pk ||= default_pk
    sequence ||= default_sequence
  end
  if pk
    if sequence
      quoted_sequence = quote_column_name(sequence)

      select_value <<-end_sql, 'Reset sequence'
        SELECT setval('#{quoted_sequence}', (SELECT COALESCE(MAX(#{quote_column_name pk})+(SELECT increment_by FROM #{quoted_sequence}), (SELECT min_value FROM #{quoted_sequence})) FROM #{quote_table_name(table)}), false)
      end_sql
    else
      @logger.warn "#{table} has primary key #{pk} with no default sequence" if @logger
    end
  end
end

#result_as_array(res) ⇒ Object

create a 2D array representing the result set



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 457

def result_as_array(res) #:nodoc:
  ary = []
  for i in 0...res.ntuples do
    ary << []
    for j in 0...res.nfields do
      ary[i] << res.getvalue(i,j)
    end
  end
  return ary
end

#rollback_db_transaction ⇒ Object

Aborts a transaction.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 509

def rollback_db_transaction
  execute "ROLLBACK"
end

#schema_search_path ⇒ Object

Returns the active schema search path.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 634

def schema_search_path
  @schema_search_path ||= query('SHOW search_path')[0][0]
end

#schema_search_path=(schema_csv) ⇒ Object

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.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 626

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) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 420

def select_rows(sql, name = nil)
  select_raw(sql, name).last
end

#supports_disable_referential_integrity? ⇒ Boolean

REFERENTIAL INTEGRITY ====================================

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 398

def supports_disable_referential_integrity?() #:nodoc:
  version = query("SHOW server_version")[0][0].split('.')
  (version[0].to_i >= 8 && version[1].to_i >= 1) ? true : false
rescue
  return false
end

#supports_insert_with_returning? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 330

def supports_insert_with_returning?
  postgresql_version >= 80200
end

#supports_migrations? ⇒ Boolean

Does PostgreSQL support migrations?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 310

def supports_migrations?
  true
end

#supports_standard_conforming_strings? ⇒ Boolean

Does PostgreSQL support standard conforming strings?

Returns:

  • (Boolean) 


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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 315

def supports_standard_conforming_strings?
  # Temporarily set the client message level above error to prevent unintentional
  # error messages in the logs when working on a PostgreSQL database server that
  # does not support standard conforming strings.
  client_min_messages_old = client_min_messages
  self.client_min_messages = 'panic'

  # postgres-pr does not raise an exception when client_min_messages is set higher
  # than error and "SHOW standard_conforming_strings" fails, but returns an empty
  # PGresult instead.
  has_support = query('SHOW standard_conforming_strings')[0][0] rescue false
  self.client_min_messages = client_min_messages_old
  has_support
end

#table_alias_length ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 336

def table_alias_length
  @table_alias_length ||= (postgresql_version >= 80000 ? query('SHOW max_identifier_length')[0][0].to_i : 63)
end

#tables(name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 568

def tables(name = nil)
  schemas = schema_search_path.split(/,/).map { |p| quote(p) }.join(',')
  query(<<-SQL, name).map { |row| row[0] }
    SELECT tablename
      FROM pg_tables
     WHERE schemaname IN (#{schemas})
  SQL
end

#type_to_sql(type, limit = nil, precision = nil, scale = nil) ⇒ Object

Maps logical Rails types to PostgreSQL-specific data types.



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 790

def type_to_sql(type, limit = nil, precision = nil, scale = nil)
  return super unless type.to_s == 'integer'

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

#update_sql(sql, name = nil) ⇒ Object

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



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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 494

def update_sql(sql, name = nil)
  super.cmd_tuples
end