Re: For index bloat: VACUUM ANALYZE vs REINDEX/CLUSTER

From: "Phoenix Kiula" <phoenix(dot)kiula(at)gmail(dot)com>
To: "Greg Williamson" <Gregory(dot)Williamson(at)digitalglobe(dot)com>
Cc: "Richard Broersma Jr" <rabroersma(at)yahoo(dot)com>, "Bill Moran" <wmoran(at)potentialtech(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: For index bloat: VACUUM ANALYZE vs REINDEX/CLUSTER
Date: 2007-09-19 05:00:15
Message-ID: e373d31e0709182200q4292aa67i3039a2df4f459a8f@mail.gmail.com
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On 19/09/2007, Gregory Williamson <Gregory(dot)Williamson(at)digitalglobe(dot)com> wrote:

...

> Can't speak directly to PostgreSQL but in Informix the fill factor is
> useful for tweaking indexes. A very high fill factor is useful for tables
> that are static -- any inserts or changes to the index trigger a *lot* of
> moving of b-tree branches. But the high fill factor means that each page has
> more useful data references in it. A very low fill factor means that pages
> are "sparse" and so inserts and updates are less likely to trigger massive
> b-tree rebalancings.

Assuming pgsql's fill factor is similar to Informix' (yes, a highly
suspect assumption), could we say:

1. A small fill factor such as 10 or 20 would be good for the index
size and will not trigger massive btree rebalancings? (I'm first
playing with a value of 60 for now and seeing how it works out...seems
ok at the moment!)

2. Is this fill factor enough to have on the table, or should I also
do a fill factor for specific indexes? Or both the table and the
index? (I have four btree indexes on the table)

Thanks

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