From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | "Jens Hartwig" <jens(dot)hartwig(at)t-systems(dot)de> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: AW: Problems with RULE |
Date: | 2001-03-07 16:43:55 |
Message-ID: | 9754.983983435@sss.pgh.pa.us |
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Lists: | pgsql-sql |
"Jens Hartwig" <jens(dot)hartwig(at)t-systems(dot)de> writes:
> What would have happened, if I executed an unconditional DELETE?
> => DELETE FROM t_xyz;
> Which statement would have been generated by PostgreSQL in this case?
Unfortunately, I didn't keep the prior discussion, so I don't remember
exactly what the rule was. But the general idea for conditional rules
is that we generate
rule-action
WHERE rule-action's-own-conditions
AND rule-condition
AND conditions-from-original-query
(repeat for each action of each relevant rule) and then if we didn't
find any relevant unconditional INSTEAD rules, we generate
original-query-action
WHERE conditions-from-original-query
AND NOT (conditions-of-conditional-INSTEAD-rules)
There's a more extensive discussion in the Programmer's Guide,
http://www.postgresql.org/devel-corner/docs/postgres/rules.html
regards, tom lane
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