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Re: WIP patch for hint bit i/o mitigation

Merlin Moncure <mmoncure@gmail.com>

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From: Merlin Moncure <mmoncure@gmail.com>
To: Atri Sharma <atri.jiit@gmail.com>
Cc: Craig Ringer <craig@2ndquadrant.com>, Amit Kapila <amit.kapila@huawei.com>, Hari Babu <haribabu.kommi@huawei.com>, Greg Smith <greg@2ndquadrant.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2013-01-18T15:36:03Z
Lists: pgsql-hackers 
On Fri, Jan 18, 2013 at 8:57 AM, Atri Sharma <atri.jiit@gmail.com> wrote:
>
> Hello all,
>
> Sorry for the delay in updating the hackers list with the current status.
>
> I recently did some profiling using perf on PostgreSQL 9.2 with and without our patch.
>
> I noticed that maximum time is being spent on heapgettup function. Further investigation and a bit of a hunch leads me to believe that we may be adversely affecting the visibility map optimisation that directly interact with the visibility functions, that our patch straight away affects.
>
> If this is the case, we may really need to get down to the design of our patch, and maybe see which visibility function/functions we are affecting, and see if we can mitigate the affect.
>
> Please let me know your inputs on this.

Any scenario that involves non-trivial amount of investigation or
development should result in us pulling the patch for rework and
resubmission in later 'fest....it's closing time as they say :-).

merlin