Re: PG15 beta1 sort performance regression due to Generation context change - Mailing list pgsql-hackers

From Tom Lane
Subject Re: PG15 beta1 sort performance regression due to Generation context change
Date
Msg-id 1347390.1653343331@sss.pgh.pa.us
Whole thread Raw
In response to Re: PG15 beta1 sort performance regression due to Generation context change  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: PG15 beta1 sort performance regression due to Generation context change  (David Rowley <dgrowleyml@gmail.com>)
List 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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