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RedHat 9 (Linux i386) - man page for set_constraints (redhat section 7)

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SET CONSTRAINTS(7)			   SQL Commands 		       SET CONSTRAINTS(7)

       SET CONSTRAINTS - set the constraint mode of the current transaction

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

       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 CON-
	      STRAINTS	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
       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.

   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.

SQL - Language Statements		    2002-11-22			       SET CONSTRAINTS(7)
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