Practical PostgreSQL

Set Constraints

Sets the constraint mode for the current transaction block.

Synopsis

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

Parameters

ALL

The keyword indicating that the mode you are specifying should be applied to all constraints within the current transaction.

constraint

The name of a specific constraint for which you wish to set the mode.

DEFERRED

The keyword indicating that constraints (or a specific constraint) shouldn’t be checked until the transaction reaches a COMMIT.

IMMEDIATE

The keyword indicating that constraints (or a specific constraint) should be checked at the end of each statement within a transaction.

Results

SET CONSTRAINTS

The message returned when a constraint mode is set successfully.

ERROR: Constraint 'constraint' does not exist

The error returned if you attempt to change the mode of a constraint that does not exist.

Description

Use the SET CONSTRAINTS command to set the constraint mode for all constraints or for a single constraint within the current transaction block. You can choose to set the constraint mode to either IMMEDIATE or DEFERRED. Use of IMMEDIATE mode will force the checking of all constraints at the end of each statement within the transaction. In DEFERRED mode, constraints are not checked until a COMMIT command is issued.

Note

PostgreSQL 7.1.x (the most current version as of the writing of this book) only supports the use of these ...