From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
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To: | Robert Treat <xzilla(at)users(dot)sourceforge(dot)net> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Free-space-map management thoughts |
Date: | 2003-02-27 16:00:11 |
Message-ID: | 11275.1046361611@sss.pgh.pa.us |
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Lists: | pgsql-hackers |
Robert Treat <xzilla(at)users(dot)sourceforge(dot)net> writes:
> Now that indexes are getting some reporting, my understanding is an
> index would report fewer pages overall than it's associated table, but
> those pages would be completely empty. However, given that they don't
> reported non-empty pages, the percentage of freeable space to total
> space would be unfairly lower (if I'm right in thinking that the back
> end will assume that non-reported pages don't have empty space in them).
> This would tend to hurt index management even though it's pages are the
> best candidates for removal (100% empty). Is this a valid concern, or am
> I misreading something?
I'm not following your point... across relations, the proposed scheme
only considers numbers of pages, not how much space is believed free in
each such page. If anything I suspect it would over-favor the indexes.
regards, tom lane
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