| From: | Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> |
|---|---|
| To: | Kyotaro Horiguchi <horikyota(dot)ntt(at)gmail(dot)com> |
| Cc: | keisuke(dot)kuroda(dot)3862(at)gmail(dot)com, tatsuro(dot)yamada(dot)tf(at)nttcom(dot)co(dot)jp, pgsql-hackers(at)lists(dot)postgresql(dot)org, amitlangote09(at)gmail(dot)com, tatsuhito(dot)kasahara(dot)rd(at)hco(dot)ntt(dot)co(dot)jp |
| Subject: | Re: Huge memory consumption on partitioned table with FKs |
| Date: | 2020-12-01 00:03:45 |
| Message-ID: | 20201201000345.GA15098@alvherre.pgsql |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On 2020-Nov-26, Kyotaro Horiguchi wrote:
> This shares RI_ConstraintInfo cache by constraints that shares the
> same parent constraints. But you forgot that the cache contains some
> members that can differ among partitions.
>
> Consider the case of attaching a partition that have experienced a
> column deletion.
I think this can be solved easily in the patch, by having
ri_BuildQueryKey() compare the parent's fk_attnums to the parent; if
they are equal then use the parent's constaint_id, otherwise use the
child constraint. That way, the cache entry is reused in the common
case where they are identical.
I would embed all this knowledge in ri_BuildQueryKey though, without
adding the new function ri_GetParentConstOid. I don't think that
function meaningful abstraction value, and instead it would make what I
suggest more difficult.
| From | Date | Subject | |
|---|---|---|---|
| Next Message | James Coleman | 2020-12-01 00:08:46 | Re: enable_incremental_sort changes query behavior |
| Previous Message | James Coleman | 2020-12-01 00:00:26 | Consider parallel for lateral subqueries with limit |