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

Methods shared by Database instances that connect to PostgreSQL.

Methods

Constants

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
FOREIGN_KEY_LIST_ON_DELETE_MAP = {'a'.freeze=>:no_action, 'r'.freeze=>:restrict, 'c'.freeze=>:cascade, 'n'.freeze=>:set_null, 'd'.freeze=>:set_default}.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 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 cons.contype = 'p' end_sql   SQL fragment for getting sequence associated with table‘s primary key, assuming it was a serial primary key column.

Public Instance methods

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 117
117:       def commit_prepared_transaction(transaction_id)
118:         run("COMMIT PREPARED #{literal(transaction_id)}")
119:       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:
      • 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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 141
141:       def create_function(name, definition, opts={})
142:         self << create_function_sql(name, definition, opts)
143:       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 152
152:       def create_language(name, opts={})
153:         self << create_language_sql(name, opts)
154:       end

Create a schema in the database. Arguments:

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 158
158:       def create_schema(name)
159:         self << create_schema_sql(name)
160:       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.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 172
172:       def create_trigger(table, name, function, opts={})
173:         self << create_trigger_sql(table, name, function, opts)
174:       end

PostgreSQL uses the :postgres database type.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 177
177:       def database_type
178:         :postgres
179:       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 187
187:       def drop_function(name, opts={})
188:         self << drop_function_sql(name, opts)
189:       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 196
196:       def drop_language(name, opts={})
197:         self << drop_language_sql(name, opts)
198:       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 205
205:       def drop_schema(name, opts={})
206:         self << drop_schema_sql(name, opts)
207:       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 215
215:       def drop_trigger(table, name, opts={})
216:         self << drop_trigger_sql(table, name, opts)
217:       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 221
221:       def foreign_key_list(table, opts={})
222:         m = output_identifier_meth
223:         im = input_identifier_meth
224:         schema, table = schema_and_table(table)
225:         range = 0...32
226: 
227:         base_ds = metadata_dataset.
228:           where(:cl__relkind=>'r', :co__contype=>'f', :cl__relname=>im.call(table)).
229:           from(:pg_constraint___co).
230:           join(:pg_class___cl, :oid=>:conrelid)
231: 
232:         # We split the parsing into two separate queries, which are merged manually later.
233:         # This is because PostgreSQL stores both the referencing and referenced columns in
234:         # arrays, and I don't know a simple way to not create a cross product, as PostgreSQL
235:         # doesn't appear to have a function that takes an array and element and gives you
236:         # the index of that element in the array.
237: 
238:         ds = base_ds.
239:           join(:pg_attribute___att, :attrelid=>:oid, :attnum=>SQL::Function.new(:ANY, :co__conkey)).
240:           order(:co__conname, SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(:co__conkey, [x]), x]}, 32, :att__attnum)).
241:           select(:co__conname___name, :att__attname___column, :co__confupdtype___on_update, :co__confdeltype___on_delete,
242:                  SQL::BooleanExpression.new(:AND, :co__condeferrable, :co__condeferred).as(:deferrable))
243: 
244:         ref_ds = base_ds.
245:           join(:pg_class___cl2, :oid=>:co__confrelid).
246:           join(:pg_attribute___att2, :attrelid=>:oid, :attnum=>SQL::Function.new(:ANY, :co__confkey)).
247:           order(:co__conname, SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(:co__conkey, [x]), x]}, 32, :att2__attnum)).
248:           select(:co__conname___name, :cl2__relname___table, :att2__attname___refcolumn)
249: 
250:         # If a schema is given, we only search in that schema, and the returned :table
251:         # entry is schema qualified as well.
252:         if schema
253:           ds = ds.join(:pg_namespace___nsp, :oid=>:cl__relnamespace).
254:             where(:nsp__nspname=>im.call(schema))
255:           ref_ds = ref_ds.join(:pg_namespace___nsp2, :oid=>:cl2__relnamespace).
256:             select_more(:nsp2__nspname___schema)
257:         end
258: 
259:         h = {}
260:         fklod_map = FOREIGN_KEY_LIST_ON_DELETE_MAP 
261:         ds.each do |row|
262:           if r = h[row[:name]]
263:             r[:columns] << m.call(row[:column])
264:           else
265:             h[row[:name]] = {:name=>m.call(row[:name]), :columns=>[m.call(row[:column])], :on_update=>fklod_map[row[:on_update]], :on_delete=>fklod_map[row[:on_delete]], :deferrable=>row[:deferrable]}
266:           end
267:         end
268:         ref_ds.each do |row|
269:           r = h[row[:name]]
270:           r[:table] ||= schema ? SQL::QualifiedIdentifier.new(m.call(row[:schema]), m.call(row[:table])) : m.call(row[:table])
271:           r[:key] ||= []
272:           r[:key] << m.call(row[:refcolumn])
273:         end
274:         h.values
275:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 278
278:       def indexes(table, opts={})
279:         m = output_identifier_meth
280:         im = input_identifier_meth
281:         schema, table = schema_and_table(table)
282:         range = 0...32
283:         attnums = server_version >= 80100 ? SQL::Function.new(:ANY, :ind__indkey) : range.map{|x| SQL::Subscript.new(:ind__indkey, [x])}
284:         ds = metadata_dataset.
285:           from(:pg_class___tab).
286:           join(:pg_index___ind, :indrelid=>:oid, im.call(table)=>:relname).
287:           join(:pg_class___indc, :oid=>:indexrelid).
288:           join(:pg_attribute___att, :attrelid=>:tab__oid, :attnum=>attnums).
289:           filter(:indc__relkind=>'i', :ind__indisprimary=>false, :indexprs=>nil, :indpred=>nil, :indisvalid=>true).
290:           order(:indc__relname, SQL::CaseExpression.new(range.map{|x| [SQL::Subscript.new(:ind__indkey, [x]), x]}, 32, :att__attnum)).
291:           select(:indc__relname___name, :ind__indisunique___unique, :att__attname___column)
292: 
293:         ds.join!(:pg_namespace___nsp, :oid=>:tab__relnamespace, :nspname=>schema.to_s) if schema
294:         ds.filter!(:indisready=>true, :indcheckxmin=>false) if server_version >= 80300
295: 
296:         indexes = {}
297:         ds.each do |r|
298:           i = indexes[m.call(r[:name])] ||= {:columns=>[], :unique=>r[:unique]}
299:           i[:columns] << m.call(r[:column])
300:         end
301:         indexes
302:       end

Dataset containing all current database locks

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 305
305:       def locks
306:         dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select(:pg_class__relname, Sequel::SQL::ColumnAll.new(:pg_locks))
307:       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 315
315:       def notify(channel, opts={})
316:         execute_ddl("NOTIFY #{channel}#{", #{literal(opts[:payload].to_s)}" if opts[:payload]}", opts)
317:       end

Return primary key for the given table.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 320
320:       def primary_key(table, opts={})
321:         quoted_table = quote_schema_table(table)
322:         @primary_keys.fetch(quoted_table) do
323:           schema, table = schema_and_table(table)
324:           sql = "#{SELECT_PK_SQL} AND pg_class.relname = #{literal(table)}"
325:           sql << "AND pg_namespace.nspname = #{literal(schema)}" if schema
326:           @primary_keys[quoted_table] = fetch(sql).single_value
327:         end
328:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 331
331:       def primary_key_sequence(table, opts={})
332:         quoted_table = quote_schema_table(table)
333:         @primary_key_sequences.fetch(quoted_table) do
334:           schema, table = schema_and_table(table)
335:           table = literal(table)
336:           sql = "#{SELECT_SERIAL_SEQUENCE_SQL} AND seq.relname = #{table}"
337:           sql << " AND name.nspname = #{literal(schema)}" if schema
338:           unless pks = fetch(sql).single_record
339:             sql = "#{SELECT_CUSTOM_SEQUENCE_SQL} AND t.relname = #{table}"
340:             sql << " AND name.nspname = #{literal(schema)}" if schema
341:             pks = fetch(sql).single_record
342:           end
343: 
344:           @primary_key_sequences[quoted_table] = if pks
345:             literal(SQL::QualifiedIdentifier.new(pks[:schema], LiteralString.new(pks[:sequence])))
346:           end
347:         end
348:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 352
352:       def reset_primary_key_sequence(table)
353:         return unless seq = primary_key_sequence(table)
354:         pk = SQL::Identifier.new(primary_key(table))
355:         db = self
356:         seq_ds = db.from(LiteralString.new(seq))
357:         get{setval(seq, db[table].select{coalesce(max(pk)+seq_ds.select{:increment_by}, seq_ds.select(:min_value))}, false)}
358:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 362
362:       def rollback_prepared_transaction(transaction_id)
363:         run("ROLLBACK PREPARED #{literal(transaction_id)}")
364:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 368
368:       def serial_primary_key_options
369:         {:primary_key => true, :serial => true, :type=>Integer}
370:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 373
373:       def server_version(server=nil)
374:         return @server_version if @server_version
375:         @server_version = synchronize(server) do |conn|
376:           (conn.server_version rescue nil) if conn.respond_to?(:server_version)
377:         end
378:         unless @server_version
379:           @server_version = if m = /PostgreSQL (\d+)\.(\d+)(?:(?:rc\d+)|\.(\d+))?/.match(fetch('SELECT version()').single_value)
380:             (m[1].to_i * 10000) + (m[2].to_i * 100) + m[3].to_i
381:           else
382:             0
383:           end
384:         end
385:         warn 'Sequel no longer supports PostgreSQL <8.2, some things may not work' if @server_version < 80200
386:         @server_version
387:       end

PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 390
390:       def supports_create_table_if_not_exists?
391:         server_version >= 90100
392:       end

PostgreSQL supports DROP TABLE IF EXISTS

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 395
395:       def supports_drop_table_if_exists?
396:         true
397:       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 401
401:       def supports_prepared_transactions?
402:         return @supports_prepared_transactions if defined?(@supports_prepared_transactions)
403:         @supports_prepared_transactions = self['SHOW max_prepared_transactions'].get.to_i > 0
404:       end

PostgreSQL supports savepoints

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 407
407:       def supports_savepoints?
408:         true
409:       end

PostgreSQL supports transaction isolation levels

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 412
412:       def supports_transaction_isolation_levels?
413:         true
414:       end

PostgreSQL supports transaction DDL statements.

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 417
417:       def supports_transactional_ddl?
418:         true
419:       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:

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 428
428:       def tables(opts={}, &block)
429:         pg_class_relname('r', opts, &block)
430:       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 434
434:       def type_supported?(type)
435:         @supported_types ||= {}
436:         @supported_types.fetch(type){@supported_types[type] = (from(:pg_type).filter(:typtype=>'b', :typname=>type.to_s).count > 0)}
437:       end

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

[Source]

     # File lib/sequel/adapters/shared/postgres.rb, line 444
444:       def views(opts={})
445:         pg_class_relname('v', opts)
446:       end

[Validate]