Re: [9.4] Make full_page_writes only settable on server start?

On Mon, Sep 2, 2013 at 10:10 PM, Jeff Davis <pgsql(at)j-davis(dot)com> wrote:
> There is a significant amount of code supporting the changing of
> full_page_writes while the server is running, including an
> XLOG_FPW_CHANGE wal record. But I don't see the use-case; surely almost
> nobody changes this on a running server, because either your filesystem
> guarantees atomic page writes for you or not.

Although this is true, the administrator's estimate of whether that
guarantee is or is not provided might not be as consistent as the
hardware behavior itself. I am generally of the feeling that having
to restart the server to change setting sucks, and while it surely
sucks less for this setting than some, mostly because few people
change this setting in the first place, I'm still not convinced that
this is moving in the right direction.

> I'd like to submit a patch to just make it into a PGC_POSTMASTER and
> remove the code to support changing it.
>
> Then, I intend to write another patch to make the full-page writes for
> checksums honor the full_page_writes setting. That will be easier to
> write once it's a PGC_POSTMASTER.

I don't think I know exactly what this means.

--
Robert Haas
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