| From: | Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(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 10:20:09 |
| Message-ID: | 53E74759.6010703@vmware.com |
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| Lists: | pgsql-hackers |
On 08/10/2014 12:22 PM, Simon Riggs wrote:
> On 8 August 2014 16:03, Heikki Linnakangas <hlinnakangas(at)vmware(dot)com> wrote:
>
>> 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.
>
> What happens if the transaction that does this aborts? Surely that
> means the new value is itself garbage? What cleans up that?
It's no different from Alvaro's patch. The updated MMTuple covers the
aborted value, but that's OK from a correctnes point of view.
- Heikki
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