Re: Partial join

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От Richard Guo
Тема Re: Partial join
Дата
Msg-id CAN_9JTwYzbHOttsZ0amun0whj5di1S+-Dec9VD3ykA+Odz4KXg@mail.gmail.com
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Ответ на Re: Partial join  (Arne Roland <A.Roland@index.de>)
Ответы Re: Partial join  (Arne Roland <A.Roland@index.de>)
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On Thu, Aug 1, 2019 at 7:46 PM Arne Roland <A.Roland@index.de> wrote:

Hello Richard,

thanks for your quick reply.


> We need to fix this.


Do you have a better idea than just keeping the old quals - possibly just the ones that get eliminated - in a separate data structure? Is the push down of quals the only case of elimination of quals, only counting the ones which happen before the restrict lists are generated?

In you case, the restriction 'sl = sl' is just not generated for the
join, because it forms an EC with const, which is not considered when
generating join clauses.

Please refer to the code snippet below:

@@ -1164,8 +1164,8 @@ generate_join_implied_equalities(PlannerInfo *root,
                List       *sublist = NIL;

                /* ECs containing consts do not need any further enforcement */
                if (ec->ec_has_const)
                        continue;

Thanks
Richard

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