Re: Subtransaction commits and Hot Standby

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Subtransaction commits and Hot Standby
Date: 2008-10-06 07:00:31
Message-ID: 1223276431.14099.22.camel@ebony.2ndQuadrant
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On Sun, 2008-10-05 at 14:51 -0400, Alvaro Herrera wrote:
> Simon Riggs wrote:
>
> > OK, spent long time testing various batching scenarios for this using a
> > custom test harness to simulate various spreads of xids in transaction
> > trees. All looks fine now.
>
> I had a look and was mostly rephrasing some comments and the README
> (hopefully I didn't make any of them worse than they were), when I
> noticed that the code to iterate thru pages could be refactored. I
> think the change makes the algorithm in TransactionIdSetTreeStatus
> easier to follow.

OK, thanks for the review.

> I also noticed that TransactionIdSetPageStatus has a "subcommit" arg
> which is unexplained. I sort-of understand the point, but I think it's
> better that you fill in the explanation in the header comment (marked
> with XXX)

I'll explain some more in the code, and in the README with worked
examples of what we need to do and why.

> I hope I didn't break the code with the new function
> set_tree_status_by_pages -- please recheck that part.

Eyeballs OK.

> I didn't test this beyond regression tests.

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

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