Re: Boolean partitions syntax

On 2018/04/10 23:37, David Rowley wrote:
> On 10 April 2018 at 23:13, Kyotaro HORIGUCHI
> <horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp> wrote:
>> Note: This is not intended to be committed this time but just for
>> information.
>>
>> At Tue, 10 Apr 2018 10:34:27 +0900 (Tokyo Standard Time), Kyotaro HORIGUCHI wrote:
>>> Just adding negation would work as a_expr is doing.
>>>
>>>> | '-' a_expr %prec UMINUS
>>>> { $$ = doNegate($2, @1); }
>>
>> a_expr fits partbound_datum_list as is but it cannot sit
>> side-by-side with MAX/MINVALUE at all. However c_expr can if
>> columnref is not excluded. The attached patch does that and
>> partition bound accepts the following syntax. (I didn't see the
>> transform side at all)
>>
>> create table p2c1 partition of p2 for values from (log(1000),0+1,0/1) to (10, 10, ('1'||'0')::int);
>
> I imagined this would have had a check for volatile functions and some
> user-friendly error message to say partition bounds must be immutable,
> but instead, it does:
>
> postgres=# create table d_p1 partition of d for values in (Random());
> ERROR: specified value cannot be cast to type double precision for column "d"
> LINE 1: create table d_p1 partition of d for values in (Random());
> ^
> DETAIL: The cast requires a non-immutable conversion.
> HINT: Try putting the literal value in single quotes.
>
> For inspiration, maybe you could follow the lead of CREATE INDEX:
>
> postgres=# create index on d ((random()));
> ERROR: functions in index expression must be marked IMMUTABLE

Hmm, I think we do already check that the *partition key* expression is
IMMUTABLE.

create table foo (a int) partition by list (random());
ERROR: functions in partition key expression must be marked IMMUTABLE

This sounds to not apply to what we'd want to do with a partition bound
expression.

Thanks,
Amit