Re: better page-level checksums - Mailing list pgsql-hackers

From Robert Haas
Subject Re: better page-level checksums
Date
Msg-id CA+TgmoZtec+o_3UYyEZLQ6AhtPSu5QS_W7Kfj07_fKKbt6YGGw@mail.gmail.com
Whole thread Raw
In response to Re: better page-level checksums  (Peter Geoghegan <pg@bowt.ie>)
Responses Re: better page-level checksums  (Michael Paquier <michael@paquier.xyz>)
Re: better page-level checksums  (Peter Geoghegan <pg@bowt.ie>)
List pgsql-hackers
On Tue, Jun 14, 2022 at 9:56 PM Peter Geoghegan <pg@bowt.ie> wrote:
> Technically we don't already do that today, with the 16-bit checksums
> that are stored in PageHeaderData.pd_checksum. But we do something
> equivalent: low-level tools can still infer that checksums must not be
> enabled on the page (really the cluster) indirectly in the event of a
> 0 checksum. A 0 value can reasonably be interpreted as a page from a
> cluster without checksums (barring page corruption). This is basically
> reasonable because our implementation of checksums is guaranteed to
> not generate 0 as a valid checksum value.

I don't think that 'pg_checksums -d' zeroes the checksum values on the
pages in the cluster.

-- 
Robert Haas
EDB: http://www.enterprisedb.com



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