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Add support for NOT ENFORCED in foreign key constraints

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This expands the NOT ENFORCED constraint flag, previously only
supported for CHECK constraints (commit ca87c415e2), to foreign key
constraints.

Normally, when a foreign key constraint is created on a table, action
and check triggers are added to maintain data integrity.  With this
patch, if a constraint is marked as NOT ENFORCED, integrity checks are
no longer required, making these triggers unnecessary.  Consequently,
when creating a NOT ENFORCED foreign key constraint, triggers will not
be created, and the constraint will be marked as NOT VALID.
Similarly, if an existing foreign key constraint is changed to NOT
ENFORCED, the associated triggers will be dropped, and the constraint
will also be marked as NOT VALID.  Conversely, if a NOT ENFORCED
foreign key constraint is changed to ENFORCED, the necessary triggers
will be created, and the will be changed to VALID by performing
necessary validation.

Since not-enforced foreign key constraints have no triggers, the
shortcut used for example in psql and pg_dump to skip looking for
foreign keys if the relation is known not to have triggers no longer
applies.  (It already didn't work for partitioned tables.)

Author: Amul Sul <sulamul@gmail.com>
Reviewed-by: Joel Jacobson <joel@compiler.org>
Reviewed-by: Andrew Dunstan <andrew@dunslane.net>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: jian he <jian.universality@gmail.com>
Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org>
Reviewed-by: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Isaac Morland <isaac.morland@gmail.com>
Reviewed-by: Alexandra Wang <alexandra.wang.oss@gmail.com>
Tested-by: Triveni N <triveni.n@enterprisedb.com>
Discussion: https://www.postgresql.org/message-id/flat/CAAJ_b962c5AcYW9KUt_R_ER5qs3fUGbe4az-SP-vuwPS-w-AGA@mail.gmail.com
This commit is contained in:
Peter Eisentraut
2025-04-02 13:30:13 +02:00
parent 327d987df1
commit eec0040c4b
19 changed files with 887 additions and 276 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
doc/src/sgml/catalogs.sgml
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@ -2620,7 +2620,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
</para>
<para>
Is the constraint enforced?
Currently, can be false only for CHECK constraints
</para></entry>
</row>

5
doc/src/sgml/ref/alter_table.sgml
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@ -58,7 +58,7 @@ ALTER TABLE [ IF EXISTS ] <replaceable class="parameter">name</replaceable>
ALTER [ COLUMN ] <replaceable class="parameter">column_name</replaceable> SET COMPRESSION <replaceable class="parameter">compression_method</replaceable>
ADD <replaceable class="parameter">table_constraint</replaceable> [ NOT VALID ]
ADD <replaceable class="parameter">table_constraint_using_index</replaceable>
ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ ENFORCED | NOT ENFORCED ]
ALTER CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> [ INHERIT | NO INHERIT ]
VALIDATE CONSTRAINT <replaceable class="parameter">constraint_name</replaceable>
DROP CONSTRAINT [ IF EXISTS ] <replaceable class="parameter">constraint_name</replaceable> [ RESTRICT | CASCADE ]
@ -589,7 +589,8 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
This form validates a foreign key or check constraint that was
previously created as <literal>NOT VALID</literal>, by scanning the
table to ensure there are no rows for which the constraint is not
satisfied. Nothing happens if the constraint is already marked valid.
satisfied. If the constraint is not enforced, an error is thrown.
Nothing happens if the constraint is already marked valid.
(See <xref linkend="sql-altertable-notes"/> below for an explanation
of the usefulness of this command.)
</para>

2
doc/src/sgml/ref/create_table.sgml
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@ -1409,7 +1409,7 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM
</para>
<para>
This is currently only supported for <literal>CHECK</literal>
This is currently only supported for foreign key and <literal>CHECK</literal>
constraints.
</para>
</listitem>