Re: Index Backward Scan fast / Index Scan slow !

From: Pailloncy Jean-Gérard <pailloncy(at)ifrance(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Index Backward Scan fast / Index Scan slow !
Date: 2004-04-13 11:12:36
Message-ID: 77EC9C09-8D3B-11D8-A5A0-000A95DE2550@ifrance.com
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> Hm, this is odd. That says you've got 349519 live index entries in
> only
> 463 actively-used index pages, or an average of 754 per page, which
> AFAICS could not fit in an 8K page. Are you using a nondefault value
> of
> BLCKSZ? If so what?
Sorry, I forgot to specify I use BLCKSZ of 32768, the same blokck's
size for newfs, the same for RAID slice's size.
I test the drive sometimes ago, and found a speed win if the slice size
the disk block size and the read block size was the same.

I do not think that a different BLCKSZ should exhibit a slowdown as the
one I found.

> If you *are* using default BLCKSZ then this index must be corrupt, and
> what you probably need to do is REINDEX it. But before you do that,
> could you send me a copy of the index file?
Do you want the index file now, or may I try something before?

Cordialement,
Jean-Gérard Pailloncy

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