/usr/man/cat.l/set_constraints.l.Z(/usr/man/cat.l/set_constraints.l.Z)

NAME

       SET CONSTRAINTS - set the constraint mode of the current transaction

SYNOPSIS

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

DESCRIPTION

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

       When you change the mode of a constraint to be IMMEDIATE, the new  con-
       straint mode takes effect retroactively: any outstanding data modifica-
       tions 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  characteris-
       tics:  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.

NOTES

       This command only alters the behavior of constraints within the current
       transaction. Thus, if you execute this command outside of a transaction
       block  (BEGIN/COMMIT  pair),  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.

COMPATIBILITY

       This command complies with the behavior defined in  the  SQL  standard,
       except  for the limitation that, in PostgreSQL, it only applies to for-
       eign-key constraints.

SQL - Language Statements         2003-11-02                SET CONSTRAINTS(l)