Module: Sequel::Postgres::DatabaseMethods

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

Constant Summary collapse

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 =

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.

(<<-end_sql
  SELECT name.nspname AS "schema",
      CASE
      WHEN split_part(pg_get_expr(def.adbin, attr.attrelid), '''', 2) ~ '.' THEN
        substr(split_part(pg_get_expr(def.adbin, attr.attrelid), '''', 2),
               strpos(split_part(pg_get_expr(def.adbin, attr.attrelid), '''', 2), '.')+1)
      ELSE split_part(pg_get_expr(def.adbin, attr.attrelid), '''', 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 pg_get_expr(def.adbin, attr.attrelid) ~* 'nextval'
end_sql
).strip.gsub(/\s+/, ' ').freeze
SELECT_PK_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.

(<<-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
).strip.gsub(/\s+/, ' ').freeze
SELECT_SERIAL_SEQUENCE_SQL =

SQL fragment for getting sequence associated with table’s primary key, assuming it was a serial primary key column.

(<<-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
).strip.gsub(/\s+/, ' ').freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#conversion_procs ⇒ Object (readonly)

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 305

def conversion_procs
  @conversion_procs
end

Instance Method Details

#add_conversion_proc(oid, callable = nil, &block) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 309

def add_conversion_proc(oid, callable=nil, &block)
  conversion_procs[oid] = callable || block
end

#add_named_conversion_proc(name, &block) ⇒ Object

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.



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

def add_named_conversion_proc(name, &block)
  unless oid = from(:pg_type).where(:typtype=>['b', 'e'], :typname=>name.to_s).get(:oid)
    raise Error, "No matching type in pg_type for #{name.inspect}"
  end
  add_conversion_proc(oid, block)
end

#check_constraints(table) ⇒ Object

A hash of metadata for CHECK constraints on the table. Keys are CHECK constraint name symbols. Values are hashes with the following keys:

:definition

An SQL fragment for the definition of the constraint

:columns

An array of column symbols for the columns referenced in the constraint, can be an empty array if the database cannot deteremine the column symbols.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 332

def check_constraints(table)
  m = output_identifier_meth

  hash = {}
  _check_constraints_ds.where_each(:conrelid=>regclass_oid(table)) do |row|
    constraint = m.call(row[:constraint])
    entry = hash[constraint] ||= {:definition=>row[:definition], :columns=>[]}
    entry[:columns] << m.call(row[:column]) if row[:column]
  end
  
  hash
end

#commit_prepared_transaction(transaction_id, opts = OPTS) ⇒ Object 



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# File 'lib/sequel/adapters/shared/postgres.rb', line 323

def commit_prepared_transaction(transaction_id, opts=OPTS)
  run("COMMIT PREPARED #{literal(transaction_id)}", opts)
end

#convert_serial_to_identity(table, opts = OPTS) ⇒ Object

Convert the first primary key column in the table from being a serial column to being an identity column. If the column is already an identity column, assume it was already converted and make no changes.

Only supported on PostgreSQL 10.2+, since on those versions Sequel will use identity columns instead of serial columns for auto incrementing primary keys. Only supported when running as a superuser, since regular users cannot modify system tables, and there is no way to keep an existing sequence when changing an existing column to be an identity column.

This method can raise an exception in at least the following cases where it may otherwise succeed (there may be additional cases not listed here):

  • The serial column was added after table creation using PostgreSQL <7.3

  • A regular index also exists on the column (such an index can probably be dropped as the primary key index should suffice)

Options:

:column

Specify the column to convert instead of using the first primary key column

:server

Run the SQL on the given server

Raises:



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# File 'lib/sequel/adapters/shared/postgres.rb', line 363

def convert_serial_to_identity(table, opts=OPTS)
  raise Error, "convert_serial_to_identity is only supported on PostgreSQL 10.2+" unless server_version >= 100002

  server = opts[:server]
  server_hash = server ? {:server=>server} : OPTS
  ds = dataset
  ds = ds.server(server) if server

  raise Error, "convert_serial_to_identity requires superuser permissions" unless ds.get{current_setting('is_superuser')} == 'on'

  table_oid = regclass_oid(table)
  im = input_identifier_meth
  unless column = (opts[:column] || ((sch = schema(table).find{|_, sc| sc[:primary_key] && sc[:auto_increment]}) && sch[0]))
    raise Error, "could not determine column to convert from serial to identity automatically"
  end
  column = im.call(column)

  column_num = ds.from(:pg_attribute).
    where(:attrelid=>table_oid, :attname=>column).
    get(:attnum)

  pg_class = Sequel.cast('pg_class', :regclass)
  res = ds.from(:pg_depend).
    where(:refclassid=>pg_class, :refobjid=>table_oid, :refobjsubid=>column_num, :classid=>pg_class, :objsubid=>0, :deptype=>%w'a i').
    select_map([:objid, Sequel.as({:deptype=>'i'}, :v)])

  case res.length
  when 0
    raise Error, "unable to find related sequence when converting serial to identity"
  when 1
    seq_oid, already_identity = res.first
  else
    raise Error, "more than one linked sequence found when converting serial to identity"
  end

  return if already_identity

  transaction(server_hash) do
    run("ALTER TABLE #{quote_schema_table(table)} ALTER COLUMN #{quote_identifier(column)} DROP DEFAULT", server_hash)

    ds.from(:pg_depend).
      where(:classid=>pg_class, :objid=>seq_oid, :objsubid=>0, :deptype=>'a').
      update(:deptype=>'i')

    ds.from(:pg_attribute).
      where(:attrelid=>table_oid, :attname=>column).
      update(:attidentity=>'d')
  end

  remove_cached_schema(table)
  nil
end

#create_function(name, definition, opts = OPTS) ⇒ Object

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.

:parallel

The thread safety attribute of the function. Should be SAFE, UNSAFE, RESTRICTED. PostgreSQL assumes UNSAFE 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 437

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

#create_language(name, opts = OPTS) ⇒ Object

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 448

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

#create_schema(name, opts = OPTS) ⇒ Object

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)



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# File 'lib/sequel/adapters/shared/postgres.rb', line 457

def create_schema(name, opts=OPTS)
  self << create_schema_sql(name, opts)
end

#create_table(name, options = OPTS, &block) ⇒ Object

Support partitions of tables using the :partition_of option.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 462

def create_table(name, options=OPTS, &block)
  if options[:partition_of]
    create_partition_of_table_from_generator(name, CreatePartitionOfTableGenerator.new(&block), options)
    return
  end

  super
end

#create_table?(name, options = OPTS, &block) ⇒ Boolean

Support partitions of tables using the :partition_of option.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 472

def create_table?(name, options=OPTS, &block)
  if options[:partition_of]
    create_table(name, options.merge!(:if_not_exists=>true), &block)
    return
  end

  super
end

#create_trigger(table, name, function, opts = OPTS) ⇒ Object

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.

:replace

Replace the trigger with the same name if it already exists (PostgreSQL 14+).

:when

A filter to use for the trigger



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# File 'lib/sequel/adapters/shared/postgres.rb', line 493

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

#database_type ⇒ Object 



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# File 'lib/sequel/adapters/shared/postgres.rb', line 497

def database_type
  :postgres
end

#defer_constraints(opts = OPTS) ⇒ Object

For constraints that are deferrable, defer constraints until transaction commit. Options:

:constraints

An identifier of the constraint, or an array of identifiers for constraints, to apply this change to specific constraints.

:server

The server/shard on which to run the query.

Examples:

DB.defer_constraints
# SET CONSTRAINTS ALL DEFERRED

DB.defer_constraints(constraints: [:c1, Sequel[:sc][:c2]])
# SET CONSTRAINTS "c1", "sc"."s2" DEFERRED



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# File 'lib/sequel/adapters/shared/postgres.rb', line 516

def defer_constraints(opts=OPTS)
  _set_constraints(' DEFERRED', opts)
end

#do(code, opts = OPTS) ⇒ Object

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.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 525

def do(code, opts=OPTS)
  language = opts[:language]
  run "DO #{"LANGUAGE #{literal(language.to_s)} " if language}#{literal(code)}"
end

#drop_function(name, opts = OPTS) ⇒ Object

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 536

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

#drop_language(name, opts = OPTS) ⇒ Object

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 545

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

#drop_schema(name, opts = OPTS) ⇒ Object

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 554

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

#drop_trigger(table, name, opts = OPTS) ⇒ Object

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 564

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

#foreign_key_list(table, opts = OPTS) ⇒ Object

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

Supports additional options:

:reverse

Instead of returning foreign keys in the current table, return foreign keys in other tables that reference the current table.

:schema

Set to true to have the :table value in the hashes be a qualified identifier. Set to false to use a separate :schema value with the related schema. Defaults to whether the given table argument is a qualified identifier.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 578

def foreign_key_list(table, opts=OPTS)
  m = output_identifier_meth
  schema, _ = opts.fetch(:schema, schema_and_table(table))

  h = {}
  fklod_map = FOREIGN_KEY_LIST_ON_DELETE_MAP 
  reverse = opts[:reverse]

  (reverse ? _reverse_foreign_key_list_ds : _foreign_key_list_ds).where_each(Sequel[:cl][:oid]=>regclass_oid(table)) do |row|
    if reverse
      key = [row[:schema], row[:table], row[:name]]
    else
      key = row[:name]
    end

    if r = h[key]
      r[:columns] << m.call(row[:column])
      r[:key] << m.call(row[:refcolumn])
    else
      entry = h[key] = {
        :name=>m.call(row[:name]),
        :columns=>[m.call(row[:column])],
        :key=>[m.call(row[:refcolumn])],
        :on_update=>fklod_map[row[:on_update]],
        :on_delete=>fklod_map[row[:on_delete]],
        :deferrable=>row[:deferrable],
        :table=>schema ? SQL::QualifiedIdentifier.new(m.call(row[:schema]), m.call(row[:table])) : m.call(row[:table]),
      }

      unless schema
        # If not combining schema information into the :table entry
        # include it as a separate entry.
        entry[:schema] = m.call(row[:schema])
      end
    end
  end

  h.values
end

#freeze ⇒ Object 



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# File 'lib/sequel/adapters/shared/postgres.rb', line 618

def freeze
  server_version
  supports_prepared_transactions?
  _schema_ds
  _select_serial_sequence_ds
  _select_custom_sequence_ds
  _select_pk_ds
  _indexes_ds
  _check_constraints_ds
  _foreign_key_list_ds
  _reverse_foreign_key_list_ds
  @conversion_procs.freeze
  super
end

#immediate_constraints(opts = OPTS) ⇒ Object

Immediately apply deferrable constraints.

:constraints

An identifier of the constraint, or an array of identifiers for constraints, to apply this change to specific constraints.

:server

The server/shard on which to run the query.

Examples:

DB.immediate_constraints
# SET CONSTRAINTS ALL IMMEDIATE

DB.immediate_constraints(constraints: [:c1, Sequel[:sc][:c2]])
# SET CONSTRAINTS "c1", "sc"."s2" IMMEDIATE



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# File 'lib/sequel/adapters/shared/postgres.rb', line 647

def immediate_constraints(opts=OPTS)
  _set_constraints(' IMMEDIATE', opts)
end

#indexes(table, opts = OPTS) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 652

def indexes(table, opts=OPTS)
  m = output_identifier_meth
  cond = {Sequel[:tab][:oid]=>regclass_oid(table, opts)}
  cond[:indpred] = nil unless opts[:include_partial]

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

#locks ⇒ Object

Dataset containing all current database locks



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# File 'lib/sequel/adapters/shared/postgres.rb', line 666

def locks
  dataset.from(:pg_class).join(:pg_locks, :relation=>:relfilenode).select{[pg_class[:relname], Sequel::SQL::ColumnAll.new(:pg_locks)]}
end

#notify(channel, opts = OPTS) ⇒ Object

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 676

def notify(channel, opts=OPTS)
  sql = String.new
  sql << "NOTIFY "
  dataset.send(:identifier_append, sql, channel)
  if payload = opts[:payload]
    sql << ", "
    dataset.literal_append(sql, payload.to_s)
  end
  execute_ddl(sql, opts)
end

#primary_key(table, opts = OPTS) ⇒ Object

Return primary key for the given table.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 688

def primary_key(table, opts=OPTS)
  quoted_table = quote_schema_table(table)
  Sequel.synchronize{return @primary_keys[quoted_table] if @primary_keys.has_key?(quoted_table)}
  value = _select_pk_ds.where_single_value(Sequel[:pg_class][:oid] => regclass_oid(table, opts))
  Sequel.synchronize{@primary_keys[quoted_table] = value}
end

#primary_key_sequence(table, opts = OPTS) ⇒ Object

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 696

def primary_key_sequence(table, opts=OPTS)
  quoted_table = quote_schema_table(table)
  Sequel.synchronize{return @primary_key_sequences[quoted_table] if @primary_key_sequences.has_key?(quoted_table)}
  cond = {Sequel[:t][:oid] => regclass_oid(table, opts)}
  value = if pks = _select_serial_sequence_ds.first(cond)
    literal(SQL::QualifiedIdentifier.new(pks[:schema], pks[:sequence]))
  elsif pks = _select_custom_sequence_ds.first(cond)
    literal(SQL::QualifiedIdentifier.new(pks[:schema], LiteralString.new(pks[:sequence])))
  end

  Sequel.synchronize{@primary_key_sequences[quoted_table] = value} if value
end

#refresh_view(name, opts = OPTS) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 715

def refresh_view(name, opts=OPTS)
  run "REFRESH MATERIALIZED VIEW#{' CONCURRENTLY' if opts[:concurrently]} #{quote_schema_table(name)}"
end

#reset_primary_key_sequence(table) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 721

def reset_primary_key_sequence(table)
  return unless seq = primary_key_sequence(table)
  pk = SQL::Identifier.new(primary_key(table))
  db = self
  s, t = schema_and_table(table)
  table = Sequel.qualify(s, t) if s

  if server_version >= 100000
    seq_ds = metadata_dataset.from(:pg_sequence).where(:seqrelid=>regclass_oid(LiteralString.new(seq)))
    increment_by = :seqincrement
    min_value = :seqmin
  # :nocov:
  else
    seq_ds = metadata_dataset.from(LiteralString.new(seq))
    increment_by = :increment_by
    min_value = :min_value
  # :nocov:
  end

  get{setval(seq, db[table].select(coalesce(max(pk)+seq_ds.select(increment_by), seq_ds.select(min_value))), false)}
end

#rollback_prepared_transaction(transaction_id, opts = OPTS) ⇒ Object 



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# File 'lib/sequel/adapters/shared/postgres.rb', line 743

def rollback_prepared_transaction(transaction_id, opts=OPTS)
  run("ROLLBACK PREPARED #{literal(transaction_id)}", opts)
end

#serial_primary_key_options ⇒ Object

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 749

def serial_primary_key_options
  # :nocov:
  auto_increment_key = server_version >= 100002 ? :identity : :serial
  # :nocov:
  {:primary_key => true, auto_increment_key => true, :type=>Integer}
end

#server_version(server = nil) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 757

def server_version(server=nil)
  return @server_version if @server_version
  ds = dataset
  ds = ds.server(server) if server
  @server_version = swallow_database_error{ds.with_sql("SELECT CAST(current_setting('server_version_num') AS integer) AS v").single_value} || 0
end

#supports_create_table_if_not_exists? ⇒ Boolean

PostgreSQL supports CREATE TABLE IF NOT EXISTS on 9.1+

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 765

def supports_create_table_if_not_exists?
  server_version >= 90100
end

#supports_deferrable_constraints? ⇒ Boolean

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

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 770

def supports_deferrable_constraints?
  server_version >= 90000
end

#supports_deferrable_foreign_key_constraints? ⇒ Boolean

PostgreSQL supports deferrable foreign key constraints.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 775

def supports_deferrable_foreign_key_constraints?
  true
end

#supports_drop_table_if_exists? ⇒ Boolean

PostgreSQL supports DROP TABLE IF EXISTS

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 780

def supports_drop_table_if_exists?
  true
end

#supports_partial_indexes? ⇒ Boolean

PostgreSQL supports partial indexes.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 785

def supports_partial_indexes?
  true
end

#supports_prepared_transactions? ⇒ Boolean

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 796

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

#supports_savepoints? ⇒ Boolean

PostgreSQL supports savepoints

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 802

def supports_savepoints?
  true
end

#supports_transaction_isolation_levels? ⇒ Boolean

PostgreSQL supports transaction isolation levels

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 807

def supports_transaction_isolation_levels?
  true
end

#supports_transactional_ddl? ⇒ Boolean

PostgreSQL supports transaction DDL statements.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 812

def supports_transactional_ddl?
  true
end

#supports_trigger_conditions? ⇒ Boolean

PostgreSQL 9.0+ supports trigger conditions.

Returns:

  • (Boolean) 


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# File 'lib/sequel/adapters/shared/postgres.rb', line 790

def supports_trigger_conditions?
  server_version >= 90000
end

#tables(opts = OPTS, &block) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 825

def tables(opts=OPTS, &block)
  pg_class_relname(['r', 'p'], opts, &block)
end

#type_supported?(type) ⇒ Boolean

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 831

def type_supported?(type)
  Sequel.synchronize{return @supported_types[type] if @supported_types.has_key?(type)}
  supported = from(:pg_type).where(:typtype=>'b', :typname=>type.to_s).count > 0
  Sequel.synchronize{return @supported_types[type] = supported}
end

#values(v) ⇒ Object

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

Raises:



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# File 'lib/sequel/adapters/shared/postgres.rb', line 844

def values(v)
  raise Error, "Cannot provide an empty array for values" if v.empty?
  @default_dataset.clone(:values=>v)
end

#views(opts = OPTS) ⇒ Object

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



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# File 'lib/sequel/adapters/shared/postgres.rb', line 857

def views(opts=OPTS)
  relkind = opts[:materialized] ? 'm' : 'v'
  pg_class_relname(relkind, opts)
end

#with_advisory_lock(lock_id, opts = OPTS) ⇒ Object

Attempt to acquire an exclusive advisory lock with the given lock_id (which should be a 64-bit integer). If successful, yield to the block, then release the advisory lock when the block exits. If unsuccessful, raise a Sequel::AdvisoryLockError.

DB.with_advisory_lock(1347){DB.get(1)}
# SELECT pg_try_advisory_lock(1357) LIMIT 1
# SELECT 1 AS v LIMIT 1
# SELECT pg_advisory_unlock(1357) LIMIT 1

Options:

:wait

Do not raise an error, instead, wait until the advisory lock can be acquired.



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# File 'lib/sequel/adapters/shared/postgres.rb', line 873

def with_advisory_lock(lock_id, opts=OPTS)
  ds = dataset
  if server = opts[:server]
    ds = ds.server(server)
  end

  synchronize(server) do |c|
    begin
      if opts[:wait]
        ds.get{pg_advisory_lock(lock_id)}
        locked = true
      else
        unless locked = ds.get{pg_try_advisory_lock(lock_id)}
          raise AdvisoryLockError, "unable to acquire advisory lock #{lock_id.inspect}"
        end
      end

      yield
    ensure
      ds.get{pg_advisory_unlock(lock_id)} if locked
    end
  end
end