Re: Separate memory contexts for relcache and catcache

On 2023-Aug-09, Melih Mutlu wrote:

> --Patch
> name | used_bytes | free_bytes | total_bytes
> -----------------------+------------+------------+-------------
> RelCacheMemoryContext | 4706464 | 3682144 | 8388608
> CatCacheMemoryContext | 3489384 | 770712 | 4260096
> index info | 2102160 | 113776 | 2215936
> CacheMemoryContext | 2336 | 5856 | 8192
> relation rules | 4416 | 3776 | 8192
> (5 rows)

Hmm, is this saying that there's too much fragmentation in the relcache
context? Maybe it would improve things to make it a SlabContext instead
of AllocSet. Or, more precisely, a bunch of SlabContexts, each with the
appropriate chunkSize for the object being stored. (I don't say this
because I know for a fact that Slab is better for these purposes; it's
just that I happened to read its comments yesterday and they stated that
it behaves better in terms of fragmentation. Maybe Andres or Tomas have
an opinion on this.)

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