pgsql-server/src backend/utils/adt/ri_triggers ...

CVSROOT:    /cvsroot
Module name:    pgsql-server
Changes by:    wieck@postgresql.org    03/04/07 16:30:38

Modified files:
    src/backend/utils/adt: ri_triggers.c
    src/test/regress/expected: foreign_key.out

Log message:
    Avoid primary key lookup (and lock) if foreign key does not change
    on UPDATE.

    This get's rid of the long standing annoyance that updating a row
    that has foreign keys locks all the referenced rows even if the
    foreign key values do not change.

    The trick is to actually do a check identical to NO ACTION after an
    eventually done UPDATE in the SET DEFAULT case. Since a SET DEFAULT
    operation should have moved referencing rows to a new "home", a following
    NO ACTION check can only fail if the column defaults of the referencing
    table resulted in the key we actually deleted. Thanks to Stephan.

    Jan