Re: Re: patch submission: truncate trailing nulls from heap rows to reduce the size of the null bitmap [Review]

Amit Kapila <amit.kapila@huawei.com>

From: Amit Kapila <amit.kapila@huawei.com>
To: "'Simon Riggs'" <simon@2ndQuadrant.com>
Cc: "'Kevin Grittner'" <kgrittn@mail.com>, <robertmhaas@gmail.com>, <josh@agliodbs.com>, <pgsql-hackers@postgresql.org>
Date: 2013-01-09T12:06:14Z
Lists: pgsql-hackers
On Wednesday, January 09, 2013 4:52 PM Simon Riggs wrote:
> On 24 December 2012 16:57, Amit Kapila <amit.kapila@huawei.com> wrote:
> 
> > Performance: Average of 3 runs of pgbench in tps
> > 9.3devel  |  with trailing null patch
> > ----------+--------------------------
> > 578.9872  |   573.4980
> 
> On balance, it would seem optimizing for this special case would
> affect everybody negatively; not much, but enough. Which means we
> should rekect this patch.
> 
> Do you have a reason why a different view might be taken?

I have tried to dig why this gap is coming. I have observed that there is
very less change in normal path.
I wanted to give it some more time to exactly find if something can be done
to avoid performance dip in normal execution.

Right now I am busy in certain other work. But definitely in coming week or
so, I shall spare time to work on it again.

With Regards,
Amit Kapila.



Commits

  1. Don't assume that a tuple's header size is unchanged during toasting.