Index for Section CONSTRAINTS

Alphabetical listing for S

Bottom of page

SET
NAME
  SET CONSTRAINTS - set the constraint mode of the current transaction

SYNOPSIS
  SET CONSTRAINTS { ALL | constraint [, ...] } { DEFERRED | IMMEDIATE }

DESCRIPTION
  SET CONSTRAINTS sets the behavior of constraint evaluation in the current
  transaction. In IMMEDIATE mode, constraints are checked at the end of each
  statement. In DEFERRED mode, constraints are not checked until transaction
  commit.

       Note: This command only alters the behavior of constraints within the
       current transaction. Thus, if you execute this command outside of an
       explicit transaction block (such as one started with BEGIN), it will
       not appear to have any effect.  If you wish to change the behavior of
       a constraint without needing to issue a SET CONSTRAINTS command in
       every transaction, specify INITIALLY DEFERRED or INITIALLY IMMEDIATE
       when you create the constraint.

  When you change the mode of a constraint to be IMMEDIATE , the new
  constraint mode takes effect retroactively: any outstanding data
  modifications that would have been checked at the end of the transaction
  (when using DEFERRED) are instead checked during the execution of the SET
  CONSTRAINTS command.

  Upon creation, a constraint is always give one of three characteristics:
  INITIALLY DEFERRED, INITIALLY IMMEDIATE DEFERRABLE, or INITIALLY IMMEDIATE
  NOT DEFERRABLE. The third class is not affected by the SET CONSTRAINTS
  command.

  Currently, only foreign key constraints are affected by this setting. Check
  and unique constraints are always effectively initially immediate not
  deferrable.

COMPATIBILITY
  SQL92, SQL99

  SET CONSTRAINTS is defined in SQL92 and SQL99. The implementation in
  PostgreSQL complies with the behavior defined in the standard, except for
  the PostgreSQL limitation that SET CONSTRAINTS cannot be applied to check
  or unique constraints.

Index for Section CONSTRAINTS

Alphabetical listing for S

Top of page