Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs.

From: Simon Riggs <simon(at)2ndQuadrant(dot)com>
To: Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [COMMITTERS] pgsql: Remove O(N^2) performance issue with multiple SAVEPOINTs.
Date: 2011-07-19 20:46:54
Message-ID: CA+U5nMLsw0FfGVAHzqa-e=L1XEy=_7tttXikLft1rb2wZ7Za+Q@mail.gmail.com
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On Tue, Jul 19, 2011 at 9:24 PM, Heikki Linnakangas
<heikki(dot)linnakangas(at)enterprisedb(dot)com> wrote:

>> You might persuade me to do it another way, but I can't see how to
>> make that way work. Your case seems a stretch.
>
> You get coincidences with memory allocations surprisingly often, because
> things tend to get allocated and free'd in chunks of certain sizes. It's
> also pretty fragile in the face of future development. It's not hard to
> imagine someone adding code in lock.c to dereference the pointer.

Then I think we need a 4th phase (would actually happen first).

I will revoke and rework.

--
 Simon Riggs                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

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