Horton

Re: Is this a problem in GenericXLogFinish()?

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Heikki Linnakangas <hlinnaka@iki.fi>, pgsql-hackers@postgresql.org
Date: 2023-10-20T16:28:17Z
Lists: pgsql-hackers 
On Thu, 2023-10-19 at 16:12 -0400, Robert Haas wrote:
> For what it's worth, though, I think it would be better to
> just make these cases exceptions to your Assert

OK, I'll probably commit something like v4 then.

I still have a question though: if a buffer is exclusive-locked,
unmodified and clean, and then the caller registers it and later does
PageSetLSN (just as if it were dirty), is that a definite bug?

There are a couple callsites where the control flow is complex enough
that it's hard to be sure the buffer is always marked dirty before
being registered (like in log_heap_visible(), as I mentioned upthread).
But those callsites are all doing PageSetLSN, unlike the hash index
case.

Regards,
	Jeff Davis

Commits

  1. Fix inconsistency with replay of hash squeeze record for clean buffers

  2. Set LSN for wbuf in _hash_freeovflpage() iff wbuf is modified.

  3. Fix an uninitialized access in hash_xlog_squeeze_page().

  4. Use REGBUF_NO_CHANGE at one more place in the hash index.

  5. Assert that buffers are marked dirty before XLogRegisterBuffer().

  6. Fix bug in GenericXLogFinish().

  7. Improve hash index bucket split behavior.