Re: Enabling Checksums - Mailing list pgsql-hackers

From Alvaro Herrera
Subject Re: Enabling Checksums
Date
Msg-id 20121109023335.GG7225@alvh.no-ip.org
Whole thread Raw
In response to Enabling Checksums  (Jeff Davis <pgsql@j-davis.com>)
Responses Re: Enabling Checksums  (Jeff Davis <pgsql@j-davis.com>)
List pgsql-hackers
Jeff Davis wrote:

> And the next question is what commands to add to change state. Ideas:
>
>    CHECKSUMS ENABLE; -- set state to "Enabling"
>    CHECKSUMS DISABLE; -- set state to "Off"
>
> And then to get to the "On" state, you have to run a system-wide VACUUM
> while in the "Enabling" state. Or, if the above syntax causes problems,
> we can make all of these into VACUUM options.

There's no such thing as a system-wide VACUUM.  The most you can get is
a database-wide VACUUM, which means you'd have to store the state
per-database somewhere (presumably the pg_database catalog), and perhaps
pg_control could have it as a system-wide value that's computed as the
minimum of all database states (so it stays "enabling" until all
databases have upgraded to "on").

--
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services



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