Re: Performance Improvement by reducing WAL for Update Operation

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Amit Kapila <amit(dot)kapila(at)huawei(dot)com>
Cc: Kyotaro HORIGUCHI <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp>, hlinnakangas(at)vmware(dot)com, noah(at)leadboat(dot)com, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Performance Improvement by reducing WAL for Update Operation
Date: 2013-01-11 15:57:53
Message-ID: CA+U5nML4hzVvO0xtR_B6wUknY7TMz7OhQmDtyw0qqGbOiNyJhQ@mail.gmail.com
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On 11 January 2013 14:24, Amit Kapila <amit(dot)kapila(at)huawei(dot)com> wrote:

> http://archives.postgresql.org/message-id/6C0B27F7206C9E4CA54AE035729E9C3828
> 52DE51(at)szxeml509-mbs
>
> 1. However Heikki has pointed, it has some problems similar to for HOT
> implementation and that is the reason we have done memcmp for HOT.
> 2. Also we have found in initial readings that this doesn't have any
> performance difference as compare to current Approach.

OK, forget that idea.

>> I've moved this to the next CF. I'm planning to review this one first.
>
> Thank you.

Just reviewing the patch now, making more sense with comments added.

In heap_delta_encode() do we store which columns have changed? Do we
store the whole new column value?

--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

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