Horton

Re: Faster "SET search_path"

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Nathan Bossart <nathandbossart@gmail.com>
Cc: Isaac Morland <isaac.morland@gmail.com>, pgsql-hackers@postgresql.org
Date: 2023-11-21T01:13:33Z
Lists: pgsql-hackers

Attachments

On Thu, 2023-11-16 at 16:46 -0800, Jeff Davis wrote:
> While I considered OOM during hash key initialization, I missed some
> other potential out-of-memory hazards. Attached a fixup patch 0003,
> which re-introduces one list copy but it simplifies things
> substantially in addition to being safer around OOM conditions.

Committed 0003 fixup.

> > > 0004: Use the same cache to optimize check_search_path().

Committed 0004.

> > > 0005: Optimize cache for repeated lookups of the same value.

Will commit 0005 soon.

I also attached a trivial 0006 patch that uses SH_STORE_HASH. I wasn't
able to show much benefit, though, even when there's a bucket
collision. Perhaps there just aren't enough elements to matter -- I
suppose there would be a benefit if there are lots of unique
search_path strings, but that doesn't seem very plausible to me. If
someone thinks it's worth committing, then I will, but I don't see any
real upside or downside.

Regards,
	Jeff Davis

Commits

  1. Fix missing invalidations for search_path cache.

  2. Optimize SearchPathCache by saving the last entry.

  3. Optimize check_search_path() by using SearchPathCache.

  4. Be more paranoid about OOM in search_path cache.

  5. Add cache for recomputeNamespacePath().

  6. Transform proconfig for faster execution.