Message-ID: <0376ae2d-570e-8837-9e93-8ada1deb2cee@enterprisedb.com>
Date: Thu, 25 May 2023 16:43:55 +0200
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Subject: Re: memory leak in trigger handling (since PG12)
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To: Andres Freund <andres@anarazel.de>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
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On 5/24/23 22:19, Andres Freund wrote:
>
> ...
> 
> Hm - stepping back a bit, why are we doing the work in ExecGetAllUpdatedCols()
> over and over?  Unless I am missing something, the result doesn't change
> across rows. And it doesn't look that cheap to compute, leaving aside the
> allocation that bms_union() does.
> 
> It's visible in profiles, not as a top entry, but still.
> 
> Perhaps the easiest to backpatch fix is to just avoid recomputing the value?
> But perhaps it'd be just as problmeatic, because callers might modify
> ExecGetAllUpdatedCols()'s return value in place...
> 

Yes, I think that's a perfectly valid point - I was actually wondering
about that too, but I was focused on fixing this in backbranches so I
left this as a future optimization (assuming it can be cached).


regards

-- 
Tomas Vondra
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