| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | David Rowley <dgrowleyml(at)gmail(dot)com> |
| Cc: | Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>, Heikki Linnakangas <hlinnaka(at)iki(dot)fi>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: PG15 beta1 sort performance regression due to Generation context change |
| Date: | 2022-05-23 22:02:11 |
| Message-ID: | 1347390.1653343331@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
I wrote:
> However, here's a different idea: how badly do we need the "size"
> field in GenerationChunk? We're not going to ever recycle the
> chunk, IIUC, so it doesn't matter exactly how big it is. When
> doing MEMORY_CONTEXT_CHECKING we'll still want requested_size,
> but that's not relevant to performance-critical cases.
Refining that a bit: we could provide the size field only when
MEMORY_CONTEXT_CHECKING and/or CLOBBER_FREED_MEMORY are defined.
That would leave us with GenerationRealloc and GenerationGetChunkSpace
not being supportable operations, but I wonder how much we need either.
BTW, shouldn't GenerationCheck be ifdef'd out if MEMORY_CONTEXT_CHECKING
isn't set? aset.c does things that way.
regards, tom lane
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