* Greg Stark <[EMAIL PROTECTED]> [081117 03:54]: > [sorry for top-posting - damn phone] > > I thought of saying that too but it doesn't really solve the problem. > Think of what happens if someone sets a hint bit on a dirty page.
If the page is dirty from a "real change", then it has a WAL backup block record already, so the torn-page on disk is going to be fixed with the wal replay ... *because* of the torn-page problem already being "solved" in PG. You don't get the hint-bits back, but that's no different from the current state. But nobody's previously cared if hint-bits wern't set on WAL replay. The tradeoff for CRC is: 1) Are hint-bits "worth saving"? (noting that with CRC the goal is the ability of detecting blocks that aren't *exactly* as we wrote them) 2) Are hint-bits "nice, but not worth IO" (noting that this case can be mitigated to only pages which are hint-bit *only* changed, not dirty with already-wal-logged changes) -- Aidan Van Dyk Create like a god, [EMAIL PROTECTED] command like a king, http://www.highrise.ca/ work like a slave.
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