module Sequel::Postgres::DatasetMethods

Instance methods for datasets that connect to a PostgreSQL database.

Constants

ACCESS_EXCLUSIVE
ACCESS_SHARE
APOS
APOS_RE
AS
BLOB_RE
BOOL_FALSE
BOOL_TRUE
COMMA
COMMA_SEPARATOR
CRLF
DELETE_CLAUSE_METHODS
DELETE_CLAUSE_METHODS_91
DOUBLE_APOS
EMPTY_STRING
EXCLUSIVE
EXPLAIN
EXPLAIN_ANALYZE
FOR_SHARE
FROM
INSERT_CLAUSE_METHODS
INSERT_CLAUSE_METHODS_91
LOCK
NULL
PAREN_CLOSE
PAREN_OPEN
PG_TIMESTAMP_FORMAT
QUERY_PLAN
ROW_EXCLUSIVE
ROW_SHARE
SELECT_CLAUSE_METHODS
SELECT_CLAUSE_METHODS_84
SHARE
SHARE_ROW_EXCLUSIVE
SHARE_UPDATE_EXCLUSIVE
SPACE
SQL_WITH_RECURSIVE
UPDATE_CLAUSE_METHODS
UPDATE_CLAUSE_METHODS_91
WINDOW
XOR_OP

Public Instance Methods

analyze() click to toggle source

Return the results of an EXPLAIN ANALYZE query as a string

# File lib/sequel/adapters/shared/postgres.rb, line 1016
def analyze
  explain(:analyze=>true)
end
complex_expression_sql_append(sql, op, args) click to toggle source

Handle converting the ruby xor operator (^) into the PostgreSQL xor operator (#).

# File lib/sequel/adapters/shared/postgres.rb, line 1022
def complex_expression_sql_append(sql, op, args)
  case op
  when :^
    j = XOR_OP
    c = false
    args.each do |a|
      sql << j if c
      literal_append(sql, a)
      c ||= true
    end
  else
    super
  end
end
explain(opts={}) click to toggle source

Return the results of an EXPLAIN query as a string

# File lib/sequel/adapters/shared/postgres.rb, line 1038
def explain(opts={})
  with_sql((opts[:analyze] ? EXPLAIN_ANALYZE : EXPLAIN) + select_sql).map(QUERY_PLAN).join(CRLF)
end
for_share() click to toggle source

Return a cloned dataset which will use FOR SHARE to lock returned rows.

# File lib/sequel/adapters/shared/postgres.rb, line 1043
def for_share
  lock_style(:share)
end
insert(*values) click to toggle source

Insert given values into the database.

# File lib/sequel/adapters/shared/postgres.rb, line 1056
def insert(*values)
  if @opts[:returning]
    # already know which columns to return, let the standard code
    # handle it
    super
  elsif @opts[:sql]
    # raw SQL used, so don't know which table is being inserted
    # into, and therefore can't determine primary key.  Run the
    # insert statement and return nil.
    super
    nil
  else
    # Force the use of RETURNING with the primary key value.
    returning(insert_pk).insert(*values){|r| return r.values.first}
  end
end
insert_select(*values) click to toggle source

Insert a record returning the record inserted

# File lib/sequel/adapters/shared/postgres.rb, line 1074
def insert_select(*values)
  returning.insert(*values){|r| return r}
end
lock(mode, opts={}) { || ... } click to toggle source

Locks all tables in the dataset's FROM clause (but not in JOINs) with the specified mode (e.g. 'EXCLUSIVE'). If a block is given, starts a new transaction, locks the table, and yields. If a block is not given just locks the tables. Note that PostgreSQL will probably raise an error if you lock the table outside of an existing transaction. Returns nil.

# File lib/sequel/adapters/shared/postgres.rb, line 1083
def lock(mode, opts={})
  if block_given? # perform locking inside a transaction and yield to block
    @db.transaction(opts){lock(mode, opts); yield}
  else
    @db.execute(LOCK % [source_list(@opts[:from]), mode], opts) # lock without a transaction
  end
  nil
end
multi_insert_sql(columns, values) click to toggle source

PostgreSQL allows inserting multiple rows at once.

# File lib/sequel/adapters/shared/postgres.rb, line 1093
def multi_insert_sql(columns, values)
  sql = LiteralString.new('VALUES ')
  expression_list_append(sql, values.map{|r| Array(r)})
  [insert_sql(columns, sql)]
end
supports_cte_in_subqueries?() click to toggle source

PostgreSQL supports using the WITH clause in subqueries if it supports using WITH at all (i.e. on PostgreSQL 8.4+).

# File lib/sequel/adapters/shared/postgres.rb, line 1101
def supports_cte_in_subqueries?
  supports_cte?
end
supports_distinct_on?() click to toggle source

DISTINCT ON is a PostgreSQL extension

# File lib/sequel/adapters/shared/postgres.rb, line 1106
def supports_distinct_on?
  true
end
supports_modifying_joins?() click to toggle source

PostgreSQL supports modifying joined datasets

# File lib/sequel/adapters/shared/postgres.rb, line 1111
def supports_modifying_joins?
  true
end
supports_regexp?() click to toggle source

PostgreSQL supports pattern matching via regular expressions

# File lib/sequel/adapters/shared/postgres.rb, line 1121
def supports_regexp?
  true
end
supports_returning?(type) click to toggle source

Returning is always supported.

# File lib/sequel/adapters/shared/postgres.rb, line 1116
def supports_returning?(type)
  true
end
supports_timestamp_timezones?() click to toggle source

PostgreSQL supports timezones in literal timestamps

# File lib/sequel/adapters/shared/postgres.rb, line 1126
def supports_timestamp_timezones?
  true
end
supports_window_functions?() click to toggle source

PostgreSQL 8.4+ supports window functions

# File lib/sequel/adapters/shared/postgres.rb, line 1131
def supports_window_functions?
  server_version >= 80400
end
truncate(opts = {}) click to toggle source

Truncates the dataset. Returns nil.

Options:

:cascade

whether to use the CASCADE option, useful when truncating

tables with Foreign Keys.
:only

truncate using ONLY, so child tables are unaffected

:restart

use RESTART IDENTITY to restart any related sequences

:only and :restart only work correctly on PostgreSQL 8.4+.

Usage:

DB[:table].truncate # TRUNCATE TABLE "table"
# => nil
DB[:table].truncate(:cascade => true, :only=>true, :restart=>true) # TRUNCATE TABLE ONLY "table" RESTART IDENTITY CASCADE
# => nil
# File lib/sequel/adapters/shared/postgres.rb, line 1150
def truncate(opts = {})
  if opts.empty?
    super()
  else
    clone(:truncate_opts=>opts).truncate
  end
end
window(name, opts) click to toggle source

Return a clone of the dataset with an addition named window that can be referenced in window functions.

# File lib/sequel/adapters/shared/postgres.rb, line 1159
def window(name, opts)
  clone(:window=>(@opts[:window]||[]) + [[name, SQL::Window.new(opts)]])
end

Protected Instance Methods

_import(columns, values, opts={}) click to toggle source

If returned primary keys are requested, use RETURNING unless already set on the dataset. If RETURNING is already set, use existing returning values. If RETURNING is only set to return a single columns, return an array of just that column. Otherwise, return an array of hashes.

# File lib/sequel/adapters/shared/postgres.rb, line 1169
def _import(columns, values, opts={})
  if @opts[:returning]
    statements = multi_insert_sql(columns, values)
    @db.transaction(opts.merge(:server=>@opts[:server])) do
      statements.map{|st| returning_fetch_rows(st)}
    end.first.map{|v| v.length == 1 ? v.values.first : v}
  elsif opts[:return] == :primary_key
    returning(insert_pk)._import(columns, values, opts)
  else
    super
  end
end