Horton

Is this a problem in GenericXLogFinish()?

Jeff Davis <pgsql@j-davis.com>

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From: Jeff Davis <pgsql@j-davis.com>
To: pgsql-hackers@postgresql.org
Date: 2023-09-22T20:52:48Z
Lists: pgsql-hackers 
src/backend/transam/README says:

  ...
  4. Mark the shared buffer(s) as dirty with MarkBufferDirty().  (This 
  must happen before the WAL record is inserted; see notes in 
  SyncOneBuffer().)
  ...

But GenericXLogFinish() does this:

  ...
  /* Insert xlog record */
  lsn = XLogInsert(RM_GENERIC_ID, 0);

  /* Set LSN and mark buffers dirty */
  for (i = 0; i < MAX_GENERIC_XLOG_PAGES; i++)
  {
      PageData   *pageData = &state->pages[i];

      if (BufferIsInvalid(pageData->buffer))
          continue;
      PageSetLSN(BufferGetPage(pageData->buffer), lsn);
      MarkBufferDirty(pageData->buffer);
  }
  END_CRIT_SECTION();

Am I missing something or is that a problem?

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.