Re: 16-bit page checksums for 9.2 - Mailing list pgsql-hackers

From Merlin Moncure
Subject Re: 16-bit page checksums for 9.2
Date
Msg-id CAHyXU0y30PcpFx5Ar0AV-0C9kBb6uLa0-H7Tr_FaUMRNHTbqsw@mail.gmail.com
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In response to Re: 16-bit page checksums for 9.2  (Andres Freund <andres@anarazel.de>)
Responses Re: 16-bit page checksums for 9.2  (Aidan Van Dyk <aidan@highrise.ca>)
Re: 16-bit page checksums for 9.2  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Fri, Jan 6, 2012 at 2:03 PM, Andres Freund <andres@anarazel.de> wrote:
>> The standby can set hint bits locally that weren't set on the data it
>> received from the master.  This will require rechecksumming and
>> rewriting the page, but obviously we can't write the WAL records
>> needed to protect those writes during recovery.  So a crash could
>> create a torn page, invalidating the checksum.
> Err. Stupid me, thanks.
>
>> Ignoring checksum errors during Hot Standby operation doesn't fix it,
>> either, because eventually you might want to promote the standby, and
>> the checksum will still be invalid.
> Its funny. I have the feeling we all are missing a very obvious brilliant
> solution to this...

Like getting rid of hint bits?

merlin


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