On Thu, Jul 16, 2020 at 8:56 PM Andrey Lepikhov <a.lepik...@postgrespro.ru> wrote: > On 7/16/20 9:55 AM, Etsuro Fujita wrote:
> >>>> On Tue, Jul 14, 2020 at 12:48 AM Alexey Kondratov > >>>> <a.kondra...@postgrespro.ru> wrote: > >>>>> Some real-life test queries show, that all single-node queries aren't > >>>>> pushed-down to the required node. For example: > >>>>> > >>>>> SELECT > >>>>> * > >>>>> FROM > >>>>> documents > >>>>> INNER JOIN users ON documents.user_id = users.id > >>>>> WHERE > >>>>> documents.company_id = 5 > >>>>> AND users.company_id = 5; > > PWJ cannot be applied > > to the join due to the limitation of the PWJ matching logic. See the > > discussion started in [1]. I think the patch in [2] would address > > this issue as well, though the patch is under review. > I think, discussion [1] is little relevant to the current task. Here we > join not on partition attribute and PWJ can't be used at all. The main point of the discussion is to determine whether PWJ can be used for a join between partitioned tables, based on EquivalenceClasses, not just join clauses created by build_joinrel_restrictlist(). For the above join, for example, the patch in [2] would derive a join clause "documents.company_id = users.company_id" from an EquivalenceClass that recorded the knowledge "documents.company_id = 5" and "users.company_id = 5", and then the planner would consider from it that PWJ can be used for the join. Best regards, Etsuro Fujita
