Re: lsyscache: free IndexAmRoutine objects returned by GetIndexAmRoutineByAmId()

Matthias van de Meent <boekewurm+postgres(at)gmail(dot)com> writes:
> On Tue, 30 Dec 2025 at 15:15, Álvaro Herrera <alvherre(at)kurilemu(dot)de> wrote:
>> One thing we can perhaps do is (in assert-enabled builds) to detect
>> whether memory usage for that context has increased during
>> InitIndexAmRoutine and raise a warning if so. Then extension authors
>> would realize this and have a chance to fix it promptly.

> Hmm, wouldn't we be able to detect changes in
> MemoryContextMemConsumed(ctx, counters) with one before and one after
> GetIndexAmRoutine(), such as included below?

I don't think we can do this, because there are effects that the
amhandler doesn't have control over. In particular, if we have to
load its pg_proc row into syscache during fmgr_info, I don't think
that is positively guaranteed not to leak anything. (This isn't
a factor for built-in AMs, which will take the fast path in
fmgr_info, but it will be an issue for extensions.)

I am not terribly concerned by one-time leaks of that sort, so
I don't really feel an urge to try to complain about them.

regards, tom lane