* Jonah H. Harris <[EMAIL PROTECTED]> [081002 14:01]: > On Thu, Oct 2, 2008 at 1:58 PM, Gregory Stark <[EMAIL PROTECTED]> wrote: > >> On recovery after a torn-page write, won't the recovery of the > >> full_page_write WAL + WAL changes get us back to the page as it was > >> before the buffer+checksum+write? > > > > Hint bit setting doesn't trigger a WAL record. > > Hence, no page image is written to WAL for later use in recovery.
OK. Got it... The block is dirty (only because of hint bits). write starts, crash, torn page, recovery doesn't "fix" the torn page... because it's never been changed (according WAL), so on next read... Without the CRC it doesn't matter, because the only change was hint-bits, so the page is half-old+half-new, but new == old+only hint-bits... Because ther'es no WAP. the torn page will be read next time that buffer is needed... a. -- 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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