Re: relpersistence and temp table

On Fri, Jul 1, 2011 at 1:59 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Jul 1, 2011 at 10:32 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Fri, Jul 1, 2011 at 8:06 AM, Amit Khandekar
>> <amit(dot)khandekar(at)enterprisedb(dot)com> wrote:
>>> In 9.1, if a table is created using an explicit pg_temp qualification,
>>> the pg_class.relpersistence is marked 'p', not 't'.
>>
>> That's a bug.  Thanks for the report.
>
> OK, so I think the problem here is that, in 9.0, it was possible to
> figure out what value relistemp should take at a very late date,
> because it was entirely a function of the schema name.  A temporary
> schema implies relistemp = true, while a non-temporary schema implies
> relistemp = false.   However, in 9.1, that clearly won't do, since
> unlogged and permanent tables can share the same schema.  Moreover, by
> the time we get as far as RelationBuildLocalRelation(), we've already
> made lots of other decisions based on relpersistence, so it seems that
> we need to make this correct as early as possible.  It's not feasible
> to do that in the parser, because the creation namespace could also
> come from search_path:
>
> SET search_path = pg_temp;
> CREATE TABLE foo (a int);
>
> So it seems we can't fix this any earlier than
> RangeVarGetCreationNamespace().  In the attached patch, I took
> basically that approach, but created a new function
> RangeVarAdjustRelationPersistence() that does the actual adjusting
> (since de-constifying RangeVarGetCreationNamespace() didn't seem
> smart), plus adds a bunch of additional sanity-checking that I
> previously overlooked.  Namely, it forbids:
>
> - creating unlogged tables in temporary schemas
> - creating relations in temporary schemas of other sessions
>
> On the other hand, it does allow CREATE TEMP TABLE pg_temp.foo(a int),
> which was somewhat pointlessly forbidden by previous releases.  In
> short, the code now checks directly what it used to check by
> inference: that you're not creating a temporary table in a permanent
> schema, or the other way around.
>
> I also rearranged a few other bits of code to make sure that the
> appropriate fixups happen BEFORE we enforce the condition that
> temporary tables mustn't be created in security-restricted contexts.

Committed.

--
Robert Haas
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