Re: Where to find information on the new HOT tables?

Dimitri Fontaine wrote:
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> Le Thursday 07 February 2008 20:43:57 Bruce Momjian, vous avez ?crit?:
> > Does the release note item on HOT need additions?
>
> If I put the release not item on HOT here:
>
> -=-=-=-
> Heap-Only Tuples (HOT) accelerate space reuse for most UPDATEs and DELETEs
> (Pavan Deolasee, with ideas from many others)
>
> UPDATEs and DELETEs leave dead tuples behind, as do failed INSERTs. Previously
> only VACUUM could reclaim space taken by dead tuples. With HOT dead tuple
> space can be reclaimed at the time of INSERT or UPDATE if no changes are made

^^^

> to indexed columns. This allows for more consistent performance. Also, HOT
> avoids adding duplicate index entries.
> -=-=-=-

OK, what I did was to add the word "automatically" at the location
indicated. Hopefully that will help.

> I'd say it only misses the transparent & automatic precision, telling the
> users they don't have anything to do about HOT: PostgreSQL is able on its own
> to decide when HOT is or is not safe to use.
> And I have to get it back that documentation is not verbose enough about how
> HOT is working, just that you have to know where to look...
>
> What about Alvaro's concern about manual vacuuming policies editing wrt to
> HOT?

I think most people will be using autovacuum, and those who aren't will
have to realize that HOT makes vacuuming less needed.

--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

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