From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Andreas Seltenreich <andreas+pg(at)gate450(dot)dyndns(dot)org> |
Cc: | Kevin Murphy <murphy(at)genome(dot)chop(dot)edu>, PostgreSQL general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: STL problem in stored procedures |
Date: | 2005-10-25 17:37:39 |
Message-ID: | 18436.1130261859@sss.pgh.pa.us |
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Lists: | pgsql-general |
Andreas Seltenreich <andreas+pg(at)gate450(dot)dyndns(dot)org> writes:
> Tom Lane schrob:
>> It *might* work to put a generic "catch/report via elog" handler around
>> each one of your entry-point functions. Haven't tried it.
> Hmm, this setup worked quite stable here for some smaller educational
> projects. The snippet I used to wrap the C++ was:
> [ snip ]
> [ some later mention of calling back into the backend for, eg, palloc ]
I was with you until that last bit. Have you covered the case where
palloc or another called-back backend routine throws an elog? AFAICS
the only clean way to do that is to PG_TRY around every such call,
throw the error as a C++ throw, catch it again at the function exit
level, re-throw as a PG longjmp :-(. Aside from the sheer tedium and
error-proneness, there's the certainty of losing quite a lot of semantic
detail in the error reports. And on top of that, what if the error was
one that the backend can't recover from except by a transaction abort?
If some level of the C++ code thinks it can catch and recover from the
error, you've left things in a pretty bad state. (palloc failure
doesn't have this risk, but a lot of other error conditions do.)
regards, tom lane
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