Re: Marking shared buffer lookup table as HASH_FIXED_SIZE

On Thu, Sep 18, 2025 at 6:14 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> Hi,
>
> On 2025-08-26 19:55:21 +0530, Ashutosh Bapat wrote:
> > StrategyInitialize() calls InitBufTable() passing the maximum number
> > of possible entries in the shared buffer lookup table. The table can
> > not have more entries than the number of available shared buffers +
> > number of partitions as explained in the comment in
> > StrategyInitialize(). If there are more than those entries something
> > is wrong with the hash table like mapping two different pages to the
> > same buffer. InitBufTable() invokes ShmemInitHash() with the same init
> > and max size. This means that the maximum number of entries are
> > allocated right from the beginning. So there should not be any need to
> > allocate more entries after initial setup. Thus the hash table
> > qualifies to be marked as HASH_FIXED_SIZE, so that we don't end up
> > with a corrupted hash table in case of a bug.
> >
> > Here's a patch to do so.
>
> Makes sense to me. Applied.

Thanks.

--
Best Wishes,
Ashutosh Bapat