From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Rafal Pietrak <rafal(at)zorro(dot)isa-geek(dot)com> |
Cc: | Jerry Sievers <jerry(at)jerrysievers(dot)com>, pgsql-general(at)postgresql(dot)org |
Subject: | Re: TRIGGER BEFORE INSERT |
Date: | 2007-01-09 15:44:16 |
Message-ID: | 7821.1168357456@sss.pgh.pa.us |
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Lists: | pgsql-general |
Rafal Pietrak <rafal(at)zorro(dot)isa-geek(dot)com> writes:
> 1. either the new value of "test_days.dnia" as already present in the
> NEW row, is not visible to "UPDATE test_utarg" sub-statement of the same
> transaction. But earlier versions of Postgres did allow for that
> visibility.
> 2. or the constrainets in earlier postgres were checked on trigger
> transaction COMMIT, not along the way; so the constraint violation
> didn't occure then.
Current versions of PG check foreign keys at the end of each
insert/update/delete statement, so your before-insert trigger is in fact
erroneous: the referenced key does not yet exist in the target table.
I think 7.2 did constraint checking only when the entire interactive
command finished, but there were enough cases where that was wrong
that we changed it.
Consider declaring the foreign-key constraint as DEFERRED.
regards, tom lane
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