Re: Problem with default partition pruning

Hosoya-san,

On 2019/03/22 15:02, Yuzuko Hosoya wrote:
> I understood Amit's proposal. But I think the issue Thibaut reported would
> occur regardless of whether clauses have OR clauses or not as follows.
> I tested a query which should output "One-Time Filter: false".
>
> # explain select * from test2_0_20 where id = 25;
> QUERY PLAN
> -----------------------------------------------------------------------
> Append (cost=0.00..25.91 rows=6 width=36)
> -> Seq Scan on test2_10_20_def (cost=0.00..25.88 rows=6 width=36)
> Filter: (id = 25)
>

Good catch, thanks.

> As Amit described in the previous email, id = 25 contradicts test2_0_20's
> partition constraint, so I think this clause should be ignored and we can
> also handle this case in the similar way as Amit proposal.
>
> I attached v1-delta-2.patch which fix the above issue.
>
> What do you think about it?

It looks fine to me. You put the code block to check whether a give
clause contradicts the partition constraint in its perfect place. :)

Maybe we should have two patches as we seem to be improving two things:

1. Patch to fix problems with default partition pruning originally
reported by Hosoya-san

2. Patch to determine if a given clause contradicts a sub-partitioned
table's partition constraint, fixing problems unearthed by Thibaut's tests

About the patch that Horiguchi-san proposed upthread, I think it has merit
that it will make partprune.c code easier to reason about, but I think we
should pursue it separately.

Thanks,
Amit