Module Sequel::DatabaseMethods
In: lib/sequel/adapters/shared/postgres.rb

Methods

Included Modules

UnmodifiedIdentifiers::DatabaseMethods

Constants

PREPARED_ARG_PLACEHOLDER = LiteralString.new('$').freeze
FOREIGN_KEY_LIST_ON_DELETE_MAP = {'a'=>:no_action, 'r'=>:restrict, 'c'=>:cascade, 'n'=>:set_null, 'd'=>:set_default}.freeze
ON_COMMIT = {:drop => 'DROP', :delete_rows => 'DELETE ROWS', :preserve_rows => 'PRESERVE ROWS'}.freeze
SELECT_CUSTOM_SEQUENCE_SQL = (<<-end_sql SELECT name.nspname AS "schema", 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 AS "sequence" FROM pg_class t JOIN pg_namespace name ON (t.relnamespace = name.oid) 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 cons.contype = 'p' AND def.adsrc ~* 'nextval' end_sql   SQL fragment for custom sequences (ones not created by serial primary key), Returning the schema and literal form of the sequence name, by parsing the column defaults table.
SELECT_PK_SQL = (<<-end_sql SELECT pg_attribute.attname AS pk FROM pg_class, pg_attribute, pg_index, pg_namespace WHERE pg_class.oid = pg_attribute.attrelid AND pg_class.relnamespace = pg_namespace.oid AND pg_class.oid = pg_index.indrelid AND pg_index.indkey[0] = pg_attribute.attnum AND pg_index.indisprimary = 't' end_sql   SQL fragment for determining primary key column for the given table. Only returns the first primary key if the table has a composite primary key.
SELECT_SERIAL_SEQUENCE_SQL = (<<-end_sql SELECT name.nspname AS "schema", seq.relname AS "sequence" FROM pg_class seq, pg_attribute attr, pg_depend dep, pg_namespace name, pg_constraint cons, pg_class t WHERE seq.oid = dep.objid AND seq.relnamespace = name.oid 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 attr.attrelid = t.oid AND cons.contype = 'p' end_sql   SQL fragment for getting sequence associated with table‘s primary key, assuming it was a serial primary key column.
VALID_CLIENT_MIN_MESSAGES = %w'DEBUG5 DEBUG4 DEBUG3 DEBUG2 DEBUG1 LOG NOTICE WARNING ERROR FATAL PANIC'.freeze.each(&:freeze)
DATABASE_ERROR_REGEXPS = [ # Add this check first, since otherwise it's possible for users to control # which exception class is generated. [/invalid input syntax/, DatabaseError], [/duplicate key value violates unique constraint/, UniqueConstraintViolation], [/violates foreign key constraint/, ForeignKeyConstraintViolation], [/violates check constraint/, CheckConstraintViolation], [/violates not-null constraint/, NotNullConstraintViolation], [/conflicting key value violates exclusion constraint/, ExclusionConstraintViolation], [/could not serialize access/, SerializationFailure], ].freeze

Attributes

conversion_procs  [R]  A hash of conversion procs, keyed by type integer (oid) and having callable values for the conversion proc for that type.

Public Instance methods

Set a conversion proc for the given oid. The callable can be passed either as a argument or a block.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 201
201:       def add_conversion_proc(oid, callable=Proc.new)
202:         conversion_procs[oid] = callable
203:       end

Add a conversion proc for a named type, using the given block. This should be used for types without fixed OIDs, which includes all types that are not included in a default PostgreSQL installation.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 208
208:       def add_named_conversion_proc(name, &block)
209:         name = name.to_s if name.is_a?(Symbol)
210:         unless oid = from(:pg_type).where(:typtype=>['b', 'e'], :typname=>name.to_s).get(:oid)
211:           raise Error, "No matching type in pg_type for #{name.inspect}"
212:         end
213:         add_conversion_proc(oid, block)
214:       end

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 216
216:       def commit_prepared_transaction(transaction_id, opts=OPTS)
217:         run("COMMIT PREPARED #{literal(transaction_id)}", opts)
218:       end

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:
1 :argument data type
2 :argument name
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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 240
240:       def create_function(name, definition, opts=OPTS)
241:         self << create_function_sql(name, definition, opts)
242:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 251
251:       def create_language(name, opts=OPTS)
252:         self << create_language_sql(name, opts)
253:       end

Create a schema in the database. Arguments:

name :Name of the schema (e.g. admin)
opts :options hash:
:if_not_exists :Don‘t raise an error if the schema already exists (PostgreSQL 9.3+)
:owner :The owner to set for the schema (defaults to current user if not specified)

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 260
260:       def create_schema(name, opts=OPTS)
261:         self << create_schema_sql(name, opts)
262:       end

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.
:when :A filter to use for the trigger

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 275
275:       def create_trigger(table, name, function, opts=OPTS)
276:         self << create_trigger_sql(table, name, function, opts)
277:       end

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 279
279:       def database_type
280:         :postgres
281:       end

Use PostgreSQL‘s DO syntax to execute an anonymous code block. The code should be the literal code string to use in the underlying procedural language. Options:

:language :The procedural language the code is written in. The PostgreSQL default is plpgsql. Can be specified as a string or a symbol.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 288
288:       def do(code, opts=OPTS)
289:         language = opts[:language]
290:         run "DO #{"LANGUAGE #{literal(language.to_s)} " if language}#{literal(code)}"
291:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 299
299:       def drop_function(name, opts=OPTS)
300:         self << drop_function_sql(name, opts)
301:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 308
308:       def drop_language(name, opts=OPTS)
309:         self << drop_language_sql(name, opts)
310:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 317
317:       def drop_schema(name, opts=OPTS)
318:         self << drop_schema_sql(name, opts)
319:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 327
327:       def drop_trigger(table, name, opts=OPTS)
328:         self << drop_trigger_sql(table, name, opts)
329:       end

Return full foreign key information using the pg system tables, including :name, :on_delete, :on_update, and :deferrable entries in the hashes.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 333
333:       def foreign_key_list(table, opts=OPTS)
334:         m = output_identifier_meth
335:         schema, _ = opts.fetch(:schema, schema_and_table(table))
336:         oid = regclass_oid(table)
337: 
338:         if server_version >= 90500
339:           cpos = Sequel.expr{array_position(co[:conkey], att[:attnum])}
340:           rpos = Sequel.expr{array_position(co[:confkey], att2[:attnum])}
341:         else
342:           range = 0...32
343:           cpos = Sequel.expr{SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(co[:conkey], [x]), x]}, 32, att[:attnum])}
344:           rpos = Sequel.expr{SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(co[:confkey], [x]), x]}, 32, att2[:attnum])}
345:         end
346: 
347:         ds = metadata_dataset.
348:           from{pg_constraint.as(:co)}.
349:           join(Sequel[:pg_class].as(:cl), :oid=>:conrelid).
350:           join(Sequel[:pg_attribute].as(:att), :attrelid=>:oid, :attnum=>SQL::Function.new(:ANY, Sequel[:co][:conkey])).
351:           join(Sequel[:pg_class].as(:cl2), :oid=>Sequel[:co][:confrelid]).
352:           join(Sequel[:pg_attribute].as(:att2), :attrelid=>:oid, :attnum=>SQL::Function.new(:ANY, Sequel[:co][:confkey])).
353:           order{[co[:conname], cpos]}.
354:           where{{
355:             cl[:relkind]=>'r',
356:             co[:contype]=>'f',
357:             cl[:oid]=>oid,
358:             cpos=>rpos
359:             }}.
360:           select{[
361:             co[:conname].as(:name),
362:             att[:attname].as(:column),
363:             co[:confupdtype].as(:on_update),
364:             co[:confdeltype].as(:on_delete),
365:             cl2[:relname].as(:table),
366:             att2[:attname].as(:refcolumn),
367:             SQL::BooleanExpression.new(:AND, co[:condeferrable], co[:condeferred]).as(:deferrable)
368:           ]}
369: 
370:         # If a schema is given, we only search in that schema, and the returned :table
371:         # entry is schema qualified as well.
372:         if schema
373:           ds = ds.join(Sequel[:pg_namespace].as(:nsp2), :oid=>Sequel[:cl2][:relnamespace]).
374:             select_append{nsp2[:nspname].as(:schema)}
375:         end
376: 
377:         h = {}
378:         fklod_map = FOREIGN_KEY_LIST_ON_DELETE_MAP 
379: 
380:         ds.each do |row|
381:           if r = h[row[:name]]
382:             r[:columns] << m.call(row[:column])
383:             r[:key] << m.call(row[:refcolumn])
384:           else
385:             h[row[:name]] = {
386:               :name=>m.call(row[:name]),
387:               :columns=>[m.call(row[:column])],
388:               :key=>[m.call(row[:refcolumn])],
389:               :on_update=>fklod_map[row[:on_update]],
390:               :on_delete=>fklod_map[row[:on_delete]],
391:               :deferrable=>row[:deferrable],
392:               :table=>schema ? SQL::QualifiedIdentifier.new(m.call(row[:schema]), m.call(row[:table])) : m.call(row[:table])
393:             }
394:           end
395:         end
396: 
397:         h.values
398:       end

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 400
400:       def freeze
401:         server_version
402:         supports_prepared_transactions?
403:         @conversion_procs.freeze
404:         super
405:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 408
408:       def indexes(table, opts=OPTS)
409:         m = output_identifier_meth
410:         oid = regclass_oid(table, opts)
411: 
412:         if server_version >= 90500
413:           order = [Sequel[:indc][:relname], Sequel.function(:array_position, Sequel[:ind][:indkey], Sequel[:att][:attnum])]
414:         else
415:           range = 0...32
416:           order = [Sequel[:indc][:relname], SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(Sequel[:ind][:indkey], [x]), x]}, 32, Sequel[:att][:attnum])]
417:           attnums = range.map{|x| SQL::Subscript.new(Sequel[:ind][:indkey], [x])} unless server_version >= 80100 
418:         end
419: 
420:         attnums ||= SQL::Function.new(:ANY, Sequel[:ind][:indkey])
421: 
422:         ds = metadata_dataset.
423:           from{pg_class.as(:tab)}.
424:           join(Sequel[:pg_index].as(:ind), :indrelid=>:oid).
425:           join(Sequel[:pg_class].as(:indc), :oid=>:indexrelid).
426:           join(Sequel[:pg_attribute].as(:att), :attrelid=>Sequel[:tab][:oid], :attnum=>attnums).
427:           left_join(Sequel[:pg_constraint].as(:con), :conname=>Sequel[:indc][:relname]).
428:           where{{
429:             indc[:relkind]=>'i',
430:             ind[:indisprimary]=>false,
431:             :indexprs=>nil,
432:             :indpred=>nil,
433:             :indisvalid=>true,
434:             tab[:oid]=>oid}}.
435:           order(*order).
436:           select{[indc[:relname].as(:name), ind[:indisunique].as(:unique), att[:attname].as(:column), con[:condeferrable].as(:deferrable)]}
437: 
438:         ds = ds.where(:indisready=>true, :indcheckxmin=>false) if server_version >= 80300
439: 
440:         indexes = {}
441:         ds.each do |r|
442:           i = indexes[m.call(r[:name])] ||= {:columns=>[], :unique=>r[:unique], :deferrable=>r[:deferrable]}
443:           i[:columns] << m.call(r[:column])
444:         end
445:         indexes
446:       end

Dataset containing all current database locks

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 449
449:       def locks
450:         dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select{[pg_class[:relname], Sequel::SQL::ColumnAll.new(:pg_locks)]}
451:       end

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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 459
459:       def notify(channel, opts=OPTS)
460:         sql = String.new
461:         sql << "NOTIFY "
462:         dataset.send(:identifier_append, sql, channel)
463:         if payload = opts[:payload]
464:           sql << ", "
465:           dataset.literal_append(sql, payload.to_s)
466:         end
467:         execute_ddl(sql, opts)
468:       end

Return primary key for the given table.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 471
471:       def primary_key(table, opts=OPTS)
472:         quoted_table = quote_schema_table(table)
473:         Sequel.synchronize{return @primary_keys[quoted_table] if @primary_keys.has_key?(quoted_table)}
474:         sql = "#{SELECT_PK_SQL} AND pg_class.oid = #{literal(regclass_oid(table, opts))}"
475:         value = fetch(sql).single_value
476:         Sequel.synchronize{@primary_keys[quoted_table] = value}
477:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 480
480:       def primary_key_sequence(table, opts=OPTS)
481:         quoted_table = quote_schema_table(table)
482:         Sequel.synchronize{return @primary_key_sequences[quoted_table] if @primary_key_sequences.has_key?(quoted_table)}
483:         sql = "#{SELECT_SERIAL_SEQUENCE_SQL} AND t.oid = #{literal(regclass_oid(table, opts))}"
484:         if pks = fetch(sql).single_record
485:           value = literal(SQL::QualifiedIdentifier.new(pks[:schema], pks[:sequence]))
486:           Sequel.synchronize{@primary_key_sequences[quoted_table] = value}
487:         else
488:           sql = "#{SELECT_CUSTOM_SEQUENCE_SQL} AND t.oid = #{literal(regclass_oid(table, opts))}"
489:           if pks = fetch(sql).single_record
490:             value = literal(SQL::QualifiedIdentifier.new(pks[:schema], LiteralString.new(pks[:sequence])))
491:             Sequel.synchronize{@primary_key_sequences[quoted_table] = value}
492:           end
493:         end
494:       end

Refresh the materialized view with the given name.

  DB.refresh_view(:items_view)
  # REFRESH MATERIALIZED VIEW items_view
  DB.refresh_view(:items_view, :concurrently=>true)
  # REFRESH MATERIALIZED VIEW CONCURRENTLY items_view

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 502
502:       def refresh_view(name, opts=OPTS)
503:         run "REFRESH MATERIALIZED VIEW#{' CONCURRENTLY' if opts[:concurrently]} #{quote_schema_table(name)}"
504:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 508
508:       def reset_primary_key_sequence(table)
509:         return unless seq = primary_key_sequence(table)
510:         pk = SQL::Identifier.new(primary_key(table))
511:         db = self
512:         seq_ds = db.from(LiteralString.new(seq))
513:         s, t = schema_and_table(table)
514:         table = Sequel.qualify(s, t) if s
515:         get{setval(seq, db[table].select{coalesce(max(pk)+seq_ds.select{:increment_by}, seq_ds.select(:min_value))}, false)}
516:       end

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 518
518:       def rollback_prepared_transaction(transaction_id, opts=OPTS)
519:         run("ROLLBACK PREPARED #{literal(transaction_id)}", opts)
520:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 524
524:       def serial_primary_key_options
525:         {:primary_key => true, :serial => true, :type=>Integer}
526:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 529
529:       def server_version(server=nil)
530:         return @server_version if @server_version
531:         @server_version = synchronize(server) do |conn|
532:           (conn.server_version rescue nil) if conn.respond_to?(:server_version)
533:         end
534:         unless @server_version
535:           @server_version = if m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
536:             (m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
537:           else
538:             0
539:           end
540:         end
541:         @server_version
542:       end

PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 545
545:       def supports_create_table_if_not_exists?
546:         server_version >= 90100
547:       end

PostgreSQL 9.0+ supports some types of deferrable constraints beyond foreign key constraints.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 550
550:       def supports_deferrable_constraints?
551:         server_version >= 90000
552:       end

PostgreSQL supports deferrable foreign key constraints.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 555
555:       def supports_deferrable_foreign_key_constraints?
556:         true
557:       end

PostgreSQL supports DROP TABLE IF EXISTS

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 560
560:       def supports_drop_table_if_exists?
561:         true
562:       end

PostgreSQL supports partial indexes.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 565
565:       def supports_partial_indexes?
566:         true
567:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 576
576:       def supports_prepared_transactions?
577:         return @supports_prepared_transactions if defined?(@supports_prepared_transactions)
578:         @supports_prepared_transactions = self['SHOW max_prepared_transactions'].get.to_i > 0
579:       end

PostgreSQL supports savepoints

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 582
582:       def supports_savepoints?
583:         true
584:       end

PostgreSQL supports transaction isolation levels

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 587
587:       def supports_transaction_isolation_levels?
588:         true
589:       end

PostgreSQL supports transaction DDL statements.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 592
592:       def supports_transactional_ddl?
593:         true
594:       end

PostgreSQL 9.0+ supports trigger conditions.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 570
570:       def supports_trigger_conditions?
571:         server_version >= 90000
572:       end

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:

:qualify :Return the tables as Sequel::SQL::QualifiedIdentifier instances, using the schema the table is located in as the qualifier.
:schema :The schema to search
:server :The server to use

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 605
605:       def tables(opts=OPTS, &block)
606:         pg_class_relname('r', opts, &block)
607:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 611
611:       def type_supported?(type)
612:         Sequel.synchronize{return @supported_types[type] if @supported_types.has_key?(type)}
613:         supported = from(:pg_type).where(:typtype=>'b', :typname=>type.to_s).count > 0
614:         Sequel.synchronize{return @supported_types[type] = supported}
615:       end

Creates a dataset that uses the VALUES clause:

  DB.values([[1, 2], [3, 4]])
  # VALUES ((1, 2), (3, 4))

  DB.values([[1, 2], [3, 4]]).order(:column2).limit(1, 1)
  # VALUES ((1, 2), (3, 4)) ORDER BY column2 LIMIT 1 OFFSET 1

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 624
624:       def values(v)
625:         @default_dataset.clone(:values=>v)
626:       end

Array of symbols specifying view names in the current database.

Options:

:materialized :Return materialized views
:qualify :Return the views as Sequel::SQL::QualifiedIdentifier instances, using the schema the view is located in as the qualifier.
:schema :The schema to search
:server :The server to use

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 636
636:       def views(opts=OPTS)
637:         relkind = opts[:materialized] ? 'm' : 'v'
638:         pg_class_relname(relkind, opts)
639:       end

[Validate]