Re: Reduce the memcpy call from SearchCatCache

Atsushi Ogawa <a_ogawa(at)hi-ho(dot)ne(dot)jp> writes:
> Tom Lane writes:
>> There are cases where cache lookups happen recursively.

> I tested regression test and pgbench. However, I did not consider
> recursive case. I revised a patch for safe recursive call.
> But I cannot find test case in which recursive call happens.

Try turning on CLOBBER_CACHE_ALWAYS or CLOBBER_CACHE_RECURSIVELY to
get a demonstration of what can happen under the right conditions.

I think the only really safe way to do what you propose would be to
refactor the ScanKey API to separate the datum values and is-null
flags from the more static parts of the data structure. That would
be a pretty large/invasive patch, and the numbers cited here don't
seem to me to justify the work. It's even possible that it could
end up being a net performance loss due to having to pass around more
pointers :-(

regards, tom lane