Обсуждение: effective_cache_size cannot be changed by a reload

On Thu, Mar 20, 2014 at 2:34 AM, Jeff Janes <jeff.janes@gmail.com> wrote:
> In 9.4dev, if the server is started with effective_cache_size = -1, then it
> cannot be changed away from that without a restart.  If you change the
> config file and do a reload or pg_reload_conf(), it ignores the change
> without comment in the logs.
>
> If you start the server with a value other than -1, then you can change the
> value by editing the file and doing a reload.  You can even change it to -1,
> and then change it back away from -1 again.

I think that's a bug. Patch attached.

> I don't know if bugs reports (without patches) against pre-release versions
> are supposed to go to hackers or to bugs.

Either works at least for me.

Regards,

--
Fujii Masao

Fujii Masao <masao.fujii@gmail.com> writes:
> On Thu, Mar 20, 2014 at 2:34 AM, Jeff Janes <jeff.janes@gmail.com> wrote:
>> In 9.4dev, if the server is started with effective_cache_size = -1, then it
>> cannot be changed away from that without a restart.

> I think that's a bug. Patch attached.

PGC_S_FILE is at least as bogus as the previous choice; for one thing,
such a source setting implies there should be a file and line number
recorded.

I think PGC_S_DYNAMIC_DEFAULT is the right thing, but I've not absorbed
much caffeine yet today.  Also, if that is the right thing, the section of
guc-file.l beginning at about line 284 needs to get taught about it; which
probably means that set_default_effective_cache_size needs a rethink so
that it can be applied and do something useful in that situation.
        regards, tom lane