Thread

Re: [v9.2] Fix leaky-view problem, part 1

Kohei KaiGai <kaigai@kaigai.gr.jp> — 2011-07-08T14:41:41Z

The attached patch is a revised one; that utilizes untransformRelOptions()
to construct a list of DefElem to be supplied into AT_ResetRelOptions
commands. It enabled me to implement more compact as I expected.

How about this approach to reset existing reloptions?

I'll consolidate part-0, 1 and 2 patches after we make fix the direction to
distinguish leaky qualifiers from others, in the thread of part-2.
Right now, I'm considering the right way to choose qualifiers to be
transformed into index scans.

Thanks,

2011/7/7 Noah Misch <noah@2ndquadrant.com>:
> On Thu, Jul 07, 2011 at 03:56:26PM +0100, Kohei KaiGai wrote:
>> 2011/7/7 Noah Misch <noah@2ndquadrant.com>:
>> > On Wed, Jul 06, 2011 at 10:25:12PM +0200, Kohei KaiGai wrote:
>> >> *** a/src/backend/commands/view.c
>> >> --- b/src/backend/commands/view.c
>> >
>> >> --- 227,257 ----
>> >>                               atcmd->def = (Node *) lfirst(c);
>> >>                               atcmds = lappend(atcmds, atcmd);
>> >>                       }
>> >>               }
>> >>
>> >>               /*
>> >> +              * If optional parameters are specified, we must set options
>> >> +              * using ALTER TABLE SET OPTION internally.
>> >> +              */
>> >> +             if (list_length(options) > 0)
>> >> +             {
>> >> +                     atcmd = makeNode(AlterTableCmd);
>> >> +                     atcmd->subtype = AT_SetRelOptions;
>> >> +                     atcmd->def = (List *)options;
>> >> +
>> >> +                     atcmds = lappend(atcmds, atcmd);
>> >> +             }
>> >> +             else
>> >> +             {
>> >> +                     atcmd = makeNode(AlterTableCmd);
>> >> +                     atcmd->subtype = AT_ResetRelOptions;
>> >> +                     atcmd->def = (Node *) list_make1(makeDefElem("security_barrier",
>> >> +                                                                                                              NULL));
>> >> +             }
>> >> +             if (atcmds != NIL)
>> >> +                     AlterTableInternal(viewOid, atcmds, true);
>> >> +
>> >> +             /*
>> >>                * Seems okay, so return the OID of the pre-existing view.
>> >>                */
>> >>               relation_close(rel, NoLock);    /* keep the lock! */
>> >
>> > That gets the job done for today, but DefineVirtualRelation() should not need
>> > to know all view options by name to simply replace the existing list with a
>> > new one.  I don't think you can cleanly use the ALTER TABLE SET/RESET code for
>> > this.  Instead, compute an option list similar to how DefineRelation() does so
>> > at tablecmds.c:491, then update pg_class.
>> >
>> My opinion is ALTER TABLE SET/RESET code should be enhanced to accept
>> an operation to reset all the existing options, rather than tricky
>> updates of pg_class.
>
> The pg_class update has ~20 lines of idiomatic code; see tablecmds.c:7931-7951.
>
>> How about an idea to add AT_ResetAllRelOptions for internal use only?
>
> If some operation is purely internal and does not otherwise benefit from the
> ALTER TABLE infrastructure, there's no benefit in involving ALTER TABLE.
> DefineVirtualRelation() uses ALTER TABLE to add columns because all that code
> needs to exist anyway.  You could make a plain function to do the update that
> gets called from both ATExecSetRelOptions() and DefineVirtualRelation().
>
> Thanks,
> nm
>
-- 
KaiGai Kohei <kaigai@kaigai.gr.jp>