Re: Re: ALTER SYSTEM SET command to change postgresql.conf parameters (RE: Proposal for Allow postgresql.conf values to be changed via SQL [review])

On Friday, August 02, 2013 5:19 PM Stephen Frost wrote:
> * Amit Kapila (amit(dot)kapila(at)huawei(dot)com) wrote:
> > Below are some points in my mind due to which I have
> > supported/implemented one-file-all-setting approach:
> > a. I had heard quite a few times that Postgres has lot of files (each
> > relation has separate file) as compare to Oracle.
> > Users feel that Oracle's table space approach is better.
>
> This is completely unrelated to this discussion, imv.
The point I wanted to convey is that having more files for database in
general is not a great idea.

> > b. While server start/Sighup, we needs to open/read/close each file
> > separately which in-itself seems to be overhead.
>
> I also don't think performance of this particular operation should be a
> high priority.

If it makes startup taking more time, then isn't it a performance critical
path?

> > I believe what Greg Stark has said in his below mail link is the more
> > appropriate way and the current patch has done that way.
> > http://www.postgresql.org/message-id/CAM-
> w4HP7=a2VowyJUD0CAZL5b8FsaHym
> > dQeouL
> > udSOhdnCw_zg(at)mail(dot)gmail(dot)com
>
> He doesn't actually provide any reasoning for it. That said, I've not
> heard any particularly good reason for having a setting per file
> either.
> This is an internal-to-PG data file and we should really implement it
> in whichever way makes the most sense for us. My general feeling is
> that one file is simpler and sufficient for the postgresql.conf-like
> parameters,

Sure, I also feel the same that if it can be addressed with single file,
then lets do that way only.

> but I wonder what we're going to do for pg_hba/pg_ident.
> Those would be good to have multiple files for because (as we saw with
> pg_authid) they could get quite large because they can have per-user
> entries in them and rewriting a large file for every change would be
> quite painful.
>
> > Also when other commercial database (Oracle) can do it with single
> > file, users will try to compare with it.
>
> To make it clear- this isn't justification for this design.

> Also, the
> notion that Oracle's *configuration* is all done with a *single-file*
> is.. laughable.

Not all Oracle's configuration, but Change of configuration parameters.
IIRC, before starting this feature I had checked Oracle's specs and it seems
to be
not doing with multiple files for Alter System. If you have doubt, I can
once again
Verify it.

With Regards,
Amit Kapila.