On Oct 2, 2008, at 3:18 PM, Alvaro Herrera wrote:
I have to admit I don't remember exactly how it worked :-) I think the idea was avoiding setting the page dirty until a certain number of hintbit setting operations had been done (which I think means it's not useful for the present purpose).
Well, it would be useful if whenever we magically decided it was time to write out a page that had only hint-bit updates we generated WAL, right? Even if it was just a no-op WAL record to ensure we had the page image in the WAL.
BTW, speaking of torn pages... I've heard that there's some serious gains to be had by turning full_page_writes to off, but I've never even dreamed of doing that because I've never seen any real sure-fire way to check that your hardware can't write torn pages. But if we have checksums enabled and checked the checksums on a block the first time we touched it during recovery, we'd be able to detect torn pages, yet still recover. That would help show that torn pages aren't possible in a particular environment (though unfortunately I don't think there's any way to actually prove that they're not).
-- Decibel!, aka Jim C. Nasby, Database Architect [EMAIL PROTECTED] Give your computer some brain candy! www.distributed.net Team #1828
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