Module: Sequel::Postgres::DatabaseMethods

Included in:
DataObjects::Postgres::DatabaseMethods, JDBC::Postgres::DatabaseMethods, Database, Swift::Postgres::DatabaseMethods
Defined in:
lib/sequel/adapters/shared/postgres.rb

Overview

Methods shared by Database instances that connect to PostgreSQL.

Constant Summary

EXCLUDE_SCHEMAS = 
/pg_*|information_schema/i
PREPARED_ARG_PLACEHOLDER = 
LiteralString.new('$').freeze
RE_CURRVAL_ERROR = 
/currval of sequence "(.*)" is not yet defined in this session|relation "(.*)" does not exist/.freeze
SYSTEM_TABLE_REGEXP = 
/^pg|sql/.freeze

Instance Method Summary (collapse)

Instance Method Details

- (Object) commit_prepared_transaction(transaction_id)

Commit an existing prepared transaction with the given transaction identifier string.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 170

def commit_prepared_transaction(transaction_id)
  run("COMMIT PREPARED #{literal(transaction_id)}")
end

- (Object) create_function(name, definition, opts = {})

Creates the function in the database. Arguments:

  • name : name of the function to create

  • definition : string definition of the function, or object file for a dynamically loaded C function.

  • opts : options hash:

    • :args : function arguments, can be either a symbol or string specifying a type or an array of 1-3 elements:

      • element 1 : argument data type

      • element 2 : argument name

      • element 3 : argument mode (e.g. in, out, inout)

    • :behavior : Should be IMMUTABLE, STABLE, or VOLATILE. PostgreSQL assumes VOLATILE by default.

    • :cost : The estimated cost of the function, used by the query planner.

    • :language : The language the function uses. SQL is the default.

    • :link_symbol : For a dynamically loaded see function, the function's link symbol if different from the definition argument.

    • :returns : The data type returned by the function. If you are using OUT or INOUT argument modes, this is ignored. Otherwise, if this is not specified, void is used by default to specify the function is not supposed to return a value.

    • :rows : The estimated number of rows the function will return. Only use if the function returns SETOF something.

    • :security_definer : Makes the privileges of the function the same as the privileges of the user who defined the function instead of the privileges of the user who runs the function. There are security implications when doing this, see the PostgreSQL documentation.

    • :set : Configuration variables to set while the function is being run, can be a hash or an array of two pairs. search_path is often used here if :security_definer is used.

    • :strict : Makes the function return NULL when any argument is NULL.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 194

def create_function(name, definition, opts={})
  self << create_function_sql(name, definition, opts)
end

- (Object) create_language(name, opts = {})

Create the procedural language in the database. Arguments:

  • name : Name of the procedural language (e.g. plpgsql)

  • opts : options hash:

    • :handler : The name of a previously registered function used as a call handler for this language.

    • :replace: Replace the installed language if it already exists (on PostgreSQL 9.0+).

    • :trusted : Marks the language being created as trusted, allowing unprivileged users to create functions using this language.

    • :validator : The name of previously registered function used as a validator of functions defined in this language.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 205

def create_language(name, opts={})
  self << create_language_sql(name, opts)
end

- (Object) create_schema(name)

Create a schema in the database. Arguments:

  • name : Name of the schema (e.g. admin)



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# File 'lib/sequel/adapters/shared/postgres.rb', line 211

def create_schema(name)
  self << create_schema_sql(name)
end

- (Object) create_trigger(table, name, function, opts = {})

Create a trigger in the database. Arguments:

  • table : the table on which this trigger operates

  • name : the name of this trigger

  • function : the function to call for this trigger, which should return type trigger.

  • opts : options hash:

    • :after : Calls the trigger after execution instead of before.

    • :args : An argument or array of arguments to pass to the function.

    • :each_row : Calls the trigger for each row instead of for each statement.

    • :events : Can be :insert, :update, :delete, or an array of any of those. Calls the trigger whenever that type of statement is used. By default, the trigger is called for insert, update, or delete.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 225

def create_trigger(table, name, function, opts={})
  self << create_trigger_sql(table, name, function, opts)
end

- (Object) database_type

PostgreSQL uses the :postgres database type.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 230

def database_type
  :postgres
end

- (Object) drop_function(name, opts = {})

Drops the function from the database. Arguments:

  • name : name of the function to drop

  • opts : options hash:

    • :args : The arguments for the function. See create_function_sql.

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 240

def drop_function(name, opts={})
  self << drop_function_sql(name, opts)
end

- (Object) drop_language(name, opts = {})

Drops a procedural language from the database. Arguments:

  • name : name of the procedural language to drop

  • opts : options hash:

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 249

def drop_language(name, opts={})
  self << drop_language_sql(name, opts)
end

- (Object) drop_schema(name, opts = {})

Drops a schema from the database. Arguments:

  • name : name of the schema to drop

  • opts : options hash:

    • :cascade : Drop all objects in this schema.

    • :if_exists : Don't raise an error if the schema doesn't exist.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 258

def drop_schema(name, opts={})
  self << drop_schema_sql(name, opts)
end

- (Object) drop_trigger(table, name, opts = {})

Drops a trigger from the database. Arguments:

  • table : table from which to drop the trigger

  • name : name of the trigger to drop

  • opts : options hash:

    • :cascade : Drop other objects depending on this function.

    • :if_exists : Don't raise an error if the function doesn't exist.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 268

def drop_trigger(table, name, opts={})
  self << drop_trigger_sql(table, name, opts)
end

- (Object) indexes(table, opts = {})

Use the pg_* system tables to determine indexes on a table



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# File 'lib/sequel/adapters/shared/postgres.rb', line 273

def indexes(table, opts={})
  m = output_identifier_meth
  im = input_identifier_meth
  schema, table = schema_and_table(table)
  range = 0...32
  attnums = server_version >= 80100 ? SQL::Function.new(:ANY, :ind__indkey) : range.map{|x| SQL::Subscript.new(:ind__indkey, [x])}
  ds = metadata_dataset.
    from(:pg_class___tab).
    join(:pg_index___ind, :indrelid=>:oid, im.call(table)=>:relname).
    join(:pg_class___indc, :oid=>:indexrelid).
    join(:pg_attribute___att, :attrelid=>:tab__oid, :attnum=>attnums).
    filter(:indc__relkind=>'i', :ind__indisprimary=>false, :indexprs=>nil, :indpred=>nil).
    order(:indc__relname, range.map{|x| [SQL::Subscript.new(:ind__indkey, [x]), x]}.case(32, :att__attnum)).
    select(:indc__relname___name, :ind__indisunique___unique, :att__attname___column)

  ds.join!(:pg_namespace___nsp, :oid=>:tab__relnamespace, :nspname=>schema.to_s) if schema
  ds.filter!(:indisvalid=>true) if server_version >= 80200
  ds.filter!(:indisready=>true, :indcheckxmin=>false) if server_version >= 80300

  indexes = {}
  ds.each do |r|
    i = indexes[m.call(r[:name])] ||= {:columns=>[], :unique=>r[:unique]}
    i[:columns] << m.call(r[:column])
  end
  indexes
end

- (Object) locks

Dataset containing all current database locks



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# File 'lib/sequel/adapters/shared/postgres.rb', line 301

def locks
  dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select(:pg_class__relname, Sequel::SQL::ColumnAll.new(:pg_locks))
end

- (Object) notify(channel, opts = {})

Notifies the given channel. See the PostgreSQL NOTIFY documentation. Options:

:payload

The payload string to use for the NOTIFY statement. Only supported in PostgreSQL 9.0+.

:server

The server to which to send the NOTIFY statement, if the sharding support is being used.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 311

def notify(channel, opts={})
  execute_ddl("NOTIFY #{channel}#{", #{literal(opts[:payload].to_s)}" if opts[:payload]}", opts)
end

- (Object) primary_key(table, opts = {})

Return primary key for the given table.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 316

def primary_key(table, opts={})
  quoted_table = quote_schema_table(table)
  return @primary_keys[quoted_table] if @primary_keys.include?(quoted_table)
  @primary_keys[quoted_table] = if conn = opts[:conn]
    conn.primary_key(*schema_and_table_quoted_strings(table))
  else
    synchronize(opts[:server]){|con| con.primary_key(*schema_and_table_quoted_strings(table))}
  end
end

- (Object) primary_key_sequence(table, opts = {})

Return the sequence providing the default for the primary key for the given table.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 327

def primary_key_sequence(table, opts={})
  quoted_table = quote_schema_table(table)
  return @primary_key_sequences[quoted_table] if @primary_key_sequences.include?(quoted_table)
  @primary_key_sequences[quoted_table] = if conn = opts[:conn]
    conn.sequence(*schema_and_table_quoted_strings(table))
  else
    synchronize(opts[:server]){|con| con.sequence(*schema_and_table_quoted_strings(table))}
  end
end

- (Object) reset_primary_key_sequence(table)

Reset the primary key sequence for the given table, baseing it on the maximum current value of the table's primary key.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 339

def reset_primary_key_sequence(table)
  pk = SQL::Identifier.new(primary_key(table))
  return unless seq = primary_key_sequence(table)
  db = self
  seq_ds = db.from(LiteralString.new(seq))
  get{setval(seq, db[table].select{coalesce(max(pk)+seq_ds.select{:increment_by}, seq_ds.select(:min_value))}, false)}
end

- (Object) rollback_prepared_transaction(transaction_id)

Rollback an existing prepared transaction with the given transaction identifier string.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 349

def rollback_prepared_transaction(transaction_id)
  run("ROLLBACK PREPARED #{literal(transaction_id)}")
end

- (Object) serial_primary_key_options

PostgreSQL uses SERIAL psuedo-type instead of AUTOINCREMENT for managing incrementing primary keys.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 355

def serial_primary_key_options
  {:primary_key => true, :serial => true, :type=>Integer}
end

- (Object) server_version(server = nil)

The version of the PostgreSQL server, used for determining capability.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 360

def server_version(server=nil)
  return @server_version if @server_version
  @server_version = synchronize(server) do |conn|
    (conn.server_version rescue nil) if conn.respond_to?(:server_version)
  end
  unless @server_version
    @server_version = if m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
      (m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
    else
      0
    end
  end
  @server_version
end

- (Boolean) supports_create_table_if_not_exists?

PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 383

def supports_create_table_if_not_exists?
  server_version >= 90100
end

- (Boolean) supports_drop_table_if_exists?

PostgreSQL supports DROP TABLE IF EXISTS on 8.2+

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 388

def supports_drop_table_if_exists?
  server_version >= 80200
end

- (Boolean) supports_prepared_transactions?

PostgreSQL supports prepared transactions (two-phase commit) if max_prepared_transactions is greater than 0.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 377

def supports_prepared_transactions?
  return @supports_prepared_transactions if defined?(@supports_prepared_transactions)
  @supports_prepared_transactions = self['SHOW max_prepared_transactions'].get.to_i > 0
end

- (Boolean) supports_savepoints?

PostgreSQL supports savepoints

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 393

def supports_savepoints?
  true
end

- (Boolean) supports_transaction_isolation_levels?

PostgreSQL supports transaction isolation levels

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 398

def supports_transaction_isolation_levels?
  true
end

- (Object) tables(opts = {}, &block)

Array of symbols specifying table names in the current database. The dataset used is yielded to the block if one is provided, otherwise, an array of symbols of table names is returned.

Options:

  • :schema - The schema to search (default_schema by default)

  • :server - The server to use



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# File 'lib/sequel/adapters/shared/postgres.rb', line 409

def tables(opts={}, &block)
  pg_class_relname('r', opts, &block)
end

- (Boolean) type_supported?(type)

Check whether the given type name string/symbol (e.g. :hstore) is supported by the database.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 415

def type_supported?(type)
  @supported_types ||= {}
  @supported_types.fetch(type){@supported_types[type] = (from(:pg_type).filter(:typtype=>'b', :typname=>type.to_s).count > 0)}
end

- (Object) views(opts = {})

Array of symbols specifying view names in the current database.

Options:

  • :schema - The schema to search (default_schema by default)

  • :server - The server to use



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# File 'lib/sequel/adapters/shared/postgres.rb', line 425

def views(opts={})
  pg_class_relname('v', opts)
end