From: | Jeff Davis <pgsql(at)j-davis(dot)com> |
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To: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Removing PD_ALL_VISIBLE |
Date: | 2012-11-22 02:24:57 |
Message-ID: | 1353551097.11440.128.camel@sussancws0025 |
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Lists: | pgsql-hackers |
Follow up to discussion:
http://archives.postgresql.org/pgsql-hackers/2012-11/msg00817.php
I worked out a patch that replaces PD_ALL_VISIBLE with calls to
visibilitymap_test. It rips out a lot of complexity, with a net drop of
about 300 lines (not a lot, but some of that code is pretty complex).
The patch is quite rough, and I haven't yet added the code to keep the
VM buffer pins around longer, but I still don't see any major problems.
I'm fairly certain that scans will not be adversely affected, and I
think that inserts/updates/deletes should be fine as well.
The main worry I have with inserts/updates/deletes is that there will be
less spatial locality for allocating new buffers or for modifying
existing buffers. So keeping a pinned VM buffer might not help as much,
because it might need to pin a different one, anyway.
Adding to January commitfest, as it's past 11/15.
Regards,
Jeff Davis
Attachment | Content-Type | Size |
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rm-pd-all-visible-20121121.patch.gz | application/x-gzip | 9.5 KB |
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