Re: pgsql: Support partition pruning at execution time

On 8 April 2018 at 10:59, David Rowley <david(dot)rowley(at)2ndquadrant(dot)com> wrote:
> Sometimes I see:
>
> relname | relallvisible
> ---------+---------------
> tprt_1 | 0
> tprt_2 | 1
>
> Other times I see:
>
> relname | relallvisible
> ---------+---------------
> tprt_1 | 0
> tprt_2 | 0

The minimum set of commands I can find to recreate this are:

drop table if exists tprt;
create table tprt (col1 int) partition by range (col1);
create table tprt_1 partition of tprt for values from (1) to (5001);
create index tprt1_idx on tprt_1 (col1);
insert into tprt values (10), (20), (501), (502), (505), (1001), (4500);
vacuum tprt; select relname,relallvisible from pg_Class where relname
like 'tprt%' and relkind = 'r';

I get relallvisible = 0 once in maybe 20 or so attempts.

I didn't manage to get the same without a partitioned table.

--
David Rowley http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services