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From Abhishek Girish <agir...@mapr.com>
Subject Re: Resetting an option
Date Mon, 10 Aug 2015 22:24:38 GMT
A session level *set* operation, by definition, should override the
corresponding system level option for the duration of the session.

Going by that, I think, a *reset* operation should default it back to the
value held by the system level option. If a user (say an admin) has updated
the corresponding system option, the reverted value would be a custom,
non-Drill-default value. And if not, the reverted value would be the
Drill-default value. This would make it simpler to manage.


On Mon, Aug 10, 2015 at 2:51 PM, Jason Altekruse <altekrusejason@gmail.com>
wrote:

> I don't know if I missed something, but the Postgres docs seem to indicate
> that there is no equivalent to the concept of a SYSTEM option that exists
> in Drill, which can be set with a query. Options can be set at server
> startup, either in a configuration file or with a command line parameter
> [2]. Once the server is running, it appears that the closest to our ALTER
> SYSTEM statement would be the feature to set options at a user or database
> level [2].
>
> Here is an excerpt from the docs on the DEFAULT option value: [1] - DEFAULT
> can be written to specify resetting the parameter to its default value
> (that is, whatever value it would have had if no SET had been executed in
> the current session).
>
> We should probably just try it out to confirm, but this statement leads me
> to believe that the option will return to the value set in the startup
> config file/parameter or what was set at the user/database level, not the
> system default. This is in agreement with my intuition on the issue, the
> whole idea behind nesting these configurations, from Drill default to
> System and then to Session would seem to be trying to provide users with
> the safest environment possible.
>
> Setting something at the system level should only be done if the
> administrator is certain that the non-standard option is a helpful
> modification for the majority of their users. Thus users can choose to
> override it, but their escape hatch should bring them back to the option
> values given by their administrator, not Drill defaults.
>
> [1] http://www.postgresql.org/docs/9.2/static/sql-set.html
> [2] http://www.postgresql.org/docs/9.2/static/config-setting.html
>
> On Mon, Aug 10, 2015 at 2:25 PM, Sudheesh Katkam <skatkam@maprtech.com>
> wrote:
>
> > Correction: currently any user can SET or RESET an option for session and
> > system.
> >
> > > On Aug 10, 2015, at 2:20 PM, Sudheesh Katkam <skatkam@maprtech.com>
> > wrote:
> > >
> > > Hey y‘all,
> > >
> > > Re DRILL-1065 <https://issues.apache.org/jira/browse/DRILL-1065>, at
> > system level (ALTER system RESET …), resetting an option would mean
> > changing the value to the default provided by Drill. But, at session
> level
> > (ALTER session RESET …), would resetting an option mean:
> > > (a) changing the value to the default provided by Drill? or,
> > > (b) changing the value to the system value, that an admin could’ve
> > changed?
> > >
> > > (b) would not allow non-admin users to know what the default is
> > (easily). However, for a given option, (a) would allow a non-admin user
> to
> > know what the default is (by resetting) and what the system setting is
> > (from sys.options). Opinions?
> > >
> > > Thank you,
> > > Sudheesh
> >
> >
>

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