Re: Page Scan Mode in Hash Index

From: Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>
To: Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Page Scan Mode in Hash Index
Date: 2017-03-23 14:59:59
Message-ID: bc21c202-3264-2960-ec44-a01ad9e73e62@redhat.com
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Hi,

On 03/22/2017 09:32 AM, Ashutosh Sharma wrote:
> Done. Please refer to the attached v2 version of patch.
>

Thanks.

>>> 1) 0001-Rewrite-hash-index-scans-to-work-a-page-at-a-time.patch: this
>>> patch rewrites the hash index scan module to work in page-at-a-time
>>> mode. It basically introduces two new functions-- _hash_readpage() and
>>> _hash_saveitem(). The former is used to load all the qualifying tuples
>>> from a target bucket or overflow page into an items array. The latter
>>> one is used by _hash_readpage to save all the qualifying tuples found
>>> in a page into an items array. Apart from that, this patch bascially
>>> cleans _hash_first(), _hash_next and hashgettuple().
>>>

0001v2:

In hashgettuple() you can remove the 'currItem' and 'offnum' from the
'else' part, and do the assignment inside

if (so->numKilled < MaxIndexTuplesPerPage)

instead.

No new comments for 0002 and 0003.

Best regards,
Jesper

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