I don't think that works anyways. No matter how thoroughly you update
all the hint bits there's still a chance someone else comes along and
sets one you missed or is setting hint bits on the same tuple at the
same time and your update gets lost.
greg
On 17 Oct 2008, at 06:59 PM, Alvaro Herrera
<[EMAIL PROTECTED]> wrote:
Simon Riggs wrote:
On Fri, 2008-10-17 at 12:26 -0300, Alvaro Herrera wrote:
Apparently the only solution in sight is to WAL-log hint bits.
Simon
opines it would be horrible from a performance standpoint to WAL-log
every hint bit set, and I think we all agree with that. So we
need to
find an alternative mechanism to WAL log hint bits.
Yes, it's clearly not acceptable bit by bit.
But perhaps writing a single WAL record if you scan whole page and
set
all bits at once. Then it makes sense in some cases.
Yeah, I thought about that too -- and perhaps give the scan some slop,
so that it will also updates some more hint bits that would be updated
in the next, say, 100 transactions. However this seems more messy
than
the other idea.
It might be possible to have a partial solution where some blocks
have
CRC checks, some not.
That's another idea but it reduces the effectiveness of the check.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
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