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Re: Re: [COMMITTERS] pgsql: Rework subtransaction commitprotocol for hot standby.

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Alvaro Herrera <alvherre(at)commandprompt(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Re: [COMMITTERS] pgsql: Rework subtransaction commitprotocol for hot standby.
Date: 2008-10-23 03:38:20
Message-ID: 1224733100.27145.558.camel@ebony.2ndQuadrant (view raw or flat)
Thread:
Lists: pgsql-committerspgsql-hackers
On Wed, 2008-10-22 at 18:53 -0400, Tom Lane wrote:
> Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> > My interest was really in maintaining ultra-correctness, while removing
> > the need to WAL log subcommits for Hot Standby. I think I achieved that,
> > almost, but if you see further optimizations that is good too.
> 
> I'm not focusing on performance here --- I'm focusing on whether I trust
> the patch at all.  

> I dislike blowing a hole that size in the sanity
> checks in TransactionIdSetStatus.  I note that the hole still isn't
> big enough, since presumably you'd have to allow ABORTED=>SUB_COMMITTED
> too.  

No, that is never required. We only set subcommitted state for a commit.

> That means that out of the four state transitions that are
> disallowed by the original coding of that Assert, you are now having to
> consider two as legal.  I don't like that, and I like even less that
> it's not even trying to determine whether this is a replay-driven
> change.

Presumably you would like to see an additional parameter to allow that
test to be more strictly determined? 

Bug fix v2 patch enclosed, mostly API changes.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Training, Services and Support

Attachment: clog_bug.v2.patch
Description: text/x-patch (16.9 KB)

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