Re: Index Scans become Seq Scans after VACUUM ANALYSE
mlw <markw@mohawksoft.com>
From: mlw <markw@mohawksoft.com>
To: Bruce Momjian <pgman@candle.pha.pa.us>
Cc: Curt Sampson <cjs@cynic.net>, Michael Loftis <mloftis@wgops.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2002-04-25T18:13:40Z
Lists: pgsql-hackers
Bruce Momjian wrote: > Now, with larger RAM and disk sizes, it may be time to consider larger > page sizes, like 32k pages. That reduces the granularity of the cache, > but it may have other performance advantages that would be worth it. > > What people are actually suggesting with the read-ahead for sequential > scans is basically a larger block size for sequential scans than for > index scans. While this makes sense, it may be better to just increase > the block size overall. I have seen performance improvements by using 16K blocks over 8K blocks in sequential scans of large tables. I am investigating the performance difference between 16K and 8K block sizes on one of my systems. I'll let you know what I see. I am using pgbench for generic performance levels. If you would like to see any extra data, just let me know.