Re: Horrible trigger performance after upgrade 8.0.12 -> 8.2.3

From: Tom Lane
Subject: Re: Horrible trigger performance after upgrade 8.0.12 -> 8.2.3
Date: ,
Msg-id: 16985.1174420705@sss.pgh.pa.us
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In response to: Horrible trigger performance after upgrade 8.0.12 -> 8.2.3  (Joseph S)
List: pgsql-performance

Joseph S <> writes:
> After upgrading to 8.2.3 INSERTs and UPDATEs on one of my tables became
> incredibly slow.  I traced the problem to one of my triggers that calls
> one of my defined functions (that is IMMUTABLE).  If I inline the
> function instead of calling it the runtime for my test update drops from
>   10261.234 ms to 564.094 ms.  The time running the trigger itself
> dropped from 9749.910 to 99.504.

With no more details than that, I don't see how you expect any useful
comments.  Let's see the code.  Also, what PG version are you comparing to?

> BTW does make any sense to bother marking trigger functions as STABLE or
> IMMUTABLE?

No, the trigger mechanisms don't pay any attention to that.  I can
hardly conceive of a useful trigger that wouldn't be VOLATILE anyway,
since side effects are more or less the point.

            regards, tom lane


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