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Re: Avoiding redundant fetches of btree index metapages

From: Simon Riggs <simon(at)2ndquadrant(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Avoiding redundant fetches of btree index metapages
Date: 2006-04-26 17:29:13
Message-ID: 1146072553.3120.16.camel@localhost.localdomain (view raw or flat)
Thread:
Lists: pgsql-hackers
On Wed, 2006-04-26 at 12:53 -0400, Tom Lane wrote:
> > So we would be able to cache other items also?
> 
> Only to the extent that you can guarantee a stale cache entry isn't a
> problem.  We've already done the analysis involved for the existing
> metapage entries, but anything else would require more thought.  (And
> more cache flush events.)

You mean performance tests! Will do.

Methinks that cache flushing is the key to performance for that idea.

> > For that case we'd save N block accesses to locate the rightmost leaf
> > page.
> 
> Surely you mean log(N).

Depends what N is. I meant the level, not the number of rows.

-- 
  Simon Riggs
  EnterpriseDB          http://www.enterprisedb.com/


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