Re: Cache Hash Index meta page.

On Tue, Jan 24, 2017 at 3:10 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> 1.
> @@ -505,26 +505,22 @@ hashbulkdelete(IndexVacuumInfo *info,

> In the above flow, do we really need an updated metapage, can't we use
> the cached one? We are already taking care of bucket split down in
> that function.

Yes, we can use the old cached metap entry, the only reason I decided
to use the latest metapage content is because the old code used to do
that. And, cached metap is used to avoid ad-hoc local saving of same
and hence unify the cached metap API. I did not intend to save the
metapage read here which I thought will not be much useful if new
buckets are added anyway we need to read the metapage at the end. I
have taken you comments now I only read metap cache which is already
set.

> 2.
> The above two chunks of code look worse as compare to your previous
> patch. I think what we can do is keep the patch ready with both the
> versions of _hash_getcachedmetap API (as you have in _v11 and _v12)
> and let committer take the final call.

_v11 API's was self-sustained one but it does not hold pins on the
metapage buffer. Whereas in _v12 we hold the pin for two consecutive
reads of metapage. I have taken your advice and producing 2 different
patches.

--
Thanks and Regards
Mithun C Y
EnterpriseDB: http://www.enterprisedb.com