From: John A Meinel <john@arbash-meinel.com>
To: Bill Chandler <billybobc1210@yahoo.com>
To: pgsql-performance@postgresql.org
Subject: Re: Index bloat problem?
Date: Thu, 21 Apr 2005 18:54:08 -0500
Message-ID: <42683D20.3060309@arbash-meinel.com> (raw)
In-Reply-To: <20050421225926.11937.qmail@web51404.mail.yahoo.com>
References: <20050421225926.11937.qmail@web51404.mail.yahoo.com>
Bill Chandler wrote:
>Mischa,
>
>Thanks. Yes, I understand that not having a large
>enough max_fsm_pages is a problem and I think that it
>is most likely the case for the client. What I wasn't
>sure of was if the index bloat we're seeing is the
>result of the "bleeding" you're talking about or
>something else.
>
>If I deleted 75% of the rows but had a max_fsm_pages
>setting that still exceeded the pages required (as
>indicated in VACUUM output), would that solve my
>indexing problem or would I still need to REINDEX
>after such a purge?
>
>regards,
>
>Bill
>
>
I don't believe VACUUM re-packs indexes. It just removes empty index
pages. So if you have 1000 index pages all with 1 entry in them, vacuum
cannot reclaim any pages. REINDEX re-packs the pages to 90% full.
fsm just needs to hold enough pages that all requests have free space
that can be used before your next vacuum. It is just a map letting
postgres know where space is available for a new fill.
John
=:->
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To: pgsql-performance@postgresql.org
Cc: john@arbash-meinel.com, billybobc1210@yahoo.com
Subject: Re: Index bloat problem?
In-Reply-To: <42683D20.3060309@arbash-meinel.com>
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