Re: Patch: Write Amplification Reduction Method (WARM)

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Pavan Deolasee <pavan(dot)deolasee(at)gmail(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Jaime Casanova <jaime(dot)casanova(at)2ndquadrant(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Patch: Write Amplification Reduction Method (WARM)
Date: 2017-03-21 19:04:48
Message-ID: 20170321190448.GF16918@momjian.us
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On Tue, Mar 21, 2017 at 11:54:25PM +0530, Pavan Deolasee wrote:
> We can also save HEAP_WARM_UPDATED flag since this is required only for
> abort-handling case. We can find a way to push that information down to the old
> tuple if UPDATE aborts and we detect the broken chain. Again, not fully thought
> through, but doable. Of course, we will have to carefully evaluate all code
> paths and make sure that we don't lose that information ever.
>
> If the consumption of bits become a deal breaker then I would first trade the
> HEAP_LATEST_TUPLE bit and then HEAP_WARM_UPDATED just from correctness
> perspective.

I don't think it makes sense to try and save bits and add complexity
when we have no idea if we will ever use them, but again, I am back to
my original question of whether we have done sufficient research, and if
everyone says "yes", I am find with that.

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Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com

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