From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
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To: | Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | heap_tuple_needs_freeze false positive |
Date: | 2012-02-02 01:01:27 |
Message-ID: | 1328144350-sup-771@alvh.no-ip.org |
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Lists: | pgsql-hackers |
Hi,
I noticed that heap_tuple_needs_freeze might return true in cases where
the Xmax is leftover junk from somebody who set HEAP_XMAX_INVALID in the
far past without resetting the Xmax value itself to Invalid. I think
this is incorrect usage; the rule, I think, is that one shouldn't even
read Xmax at all unless HEAP_XMAX_INVALID is reset.
This might cause unnecessary acquisitions of the cleanup lock, if a
tuple is deemed freezable when in fact it isn't.
Suggested patch attached. I'd backpatch this as far as it applies
cleanly.
--
Álvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Attachment | Content-Type | Size |
---|---|---|
heap_tuple_needs_freeze.patch | application/octet-stream | 887 bytes |
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