Re: What needs to be done for real Partitioning?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Stacy White" <harsh(at)computer(dot)org>
Cc: "Alvaro Herrera" <alvherre(at)dcc(dot)uchile(dot)cl>, "PFC" <lists(at)boutiquenumerique(dot)com>, "Josh Berkus" <josh(at)agliodbs(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: What needs to be done for real Partitioning?
Date: 2005-03-20 23:01:49
Message-ID: 14172.1111359709@sss.pgh.pa.us
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"Stacy White" <harsh(at)computer(dot)org> writes:
> FWIW, we see large benefits from partitioning other than the ability to
> easily drop data, for example:

> - We can vacuum only the active portions of a table
> - Postgres automatically keeps related records clustered together on disk,
> which makes it more likely that the blocks used by common queries can be
> found in cache
> - The query engine uses full table scans on the relevant sections of data,
> and quickly skips over the irrelevant sections
> - 'CLUSTER'ing a single partition is likely to be significantly more
> performant than clustering a large table

Global indexes would seriously reduce the performance of both vacuum and
cluster for a single partition, and if you want seq scans you don't need
an index for that at all. So the above doesn't strike me as a strong
argument for global indexes ...

regards, tom lane

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