Re: Add pgstathashindex() to get hash index table statistics.

On Mon, Feb 6, 2017 at 10:06 AM, Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:
> On Sat, Feb 4, 2017 at 1:12 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>>
>> Committed with those changes.
>
> Thanks for above corrections and commit. But, There are couple of
> things that we might have to change once the patch for 'WAL in Hash
> Indexes' gets checked-in.
>
> 1) The test-case result needs to be changed because there won't be any
> WARNING message : "WARNING: hash indexes are not WAL-logged and their
> use is discouraged".
>

I think this should be changed in WAL patch itself, no need to handle
it separately.

> 2) From WAL patch for Hash Indexes onwards, we won't have any zero
> pages in Hash Indexes so I don't think we need to have column showing
> zero pages (zero_pages). When working on WAL in hash indexes, we found
> that WAL routine 'XLogReadBufferExtended' does not expect a page to be
> completely zero page else it returns Invalid Buffer. To fix this, we
> started initializing freed overflow page and newly allocated bucket
> pages using _hash_pageinit() hence I don't think there will be any
> zero pages from here onwards.
>

Can't we use PageIsEmpty() to show such information?

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com