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

On Sun, Feb 5, 2017 at 11:36 PM, Ashutosh Sharma <ashu.coek88@gmail.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".
>
> 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.

Maybe we should call them "unused pages".  Those will presumably still exist.

-- 
Robert Haas
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