From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
---|---|
To: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
Cc: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Nicolas Barbier <nicolas(dot)barbier(at)gmail(dot)com>, Claudio Freire <klaussfreire(at)gmail(dot)com>, Josh Berkus <josh(at)agliodbs(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: Minmax indexes |
Date: | 2014-08-10 09:42:52 |
Message-ID: | CA+U5nM++DdwTp5gDxmncFX_sT7Bc11hT0Pht3=BkYW_c2An+eg@mail.gmail.com |
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On 8 August 2014 16:03, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> wrote:
> I couldn't resist starting to hack on this, and implemented the scheme I've
> been having in mind:
>
> 1. MMTuple contains the block number of the heap page (range) that the tuple
> represents. Vacuum is no longer needed to clean up old tuples; when an index
> tuples is updated, the old tuple is deleted atomically with the insertion of
> a new tuple and updating the revmap, so no garbage is left behind.
>
> 2. LockTuple is gone. When following the pointer from revmap to MMTuple, the
> block number is used to check that you land on the right tuple. If not, the
> search is started over, looking at the revmap again.
Part 2 sounds interesting, especially because of the reduction in CPU
that it might allow.
Part 1 doesn't sound good yet.
Are they connected?
More importantly, can't we tweak this after commit? Delaying commit
just means less time for other people to see, test, understand tune
and fix. I see you (Heikki) doing lots of incremental development,
lots of small commits. Can't we do this one the same?
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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