Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables

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От Amit Khandekar
Тема Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables
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Msg-id CAJ3gD9cHpzyeAVxDJxYTs3ghQ1jUQJPznW6jjvQ0p1Jkmx6eMw@mail.gmail.com
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Ответ на Re: [HACKERS] Partition-wise join for join between (declaratively)partitioned tables  (Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>)
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On 13 September 2017 at 13:05, Ashutosh Bapat
<ashutosh.bapat@enterprisedb.com> wrote:
> On Wed, Sep 13, 2017 at 12:32 PM, Amit Khandekar <amitdkhan.pg@gmail.com> wrote:
>> Hi,
>>
>> Rafia had done some testing on TPCH queries using Partition-wise join
>> patch along with Parallel Append patch.
>>
>> There, we had observed that for query 4, even though the partition
>> wise joins are under a Parallel Append, the join are all non-partial.
>>
>> Specifically, the partition-wise join has non-partial nested loop
>> joins when actually it was expected to have partial nested loop joins.
>> (The difference can be seen by the observation that the outer relation
>> of that join is scanned by non-parallel Bitmap Heap scan when it
>> should have used Parallel Bitmap Heap Scan).
>>
>> Here is the detailed analysis , including where I think is the issue :
>>
>> https://www.postgresql.org/message-id/CAJ3gD9cZms1ND3p%3DNN%3DhDYDFt_SeKq1htMBhbj85bOmvJwY5fg%40mail.gmail.com
>>
>> All the TPCH results are posted in the same above mail thread.
>
> Can you please check if the attached patch fixes the issue.

Thanks Ashutosh. Yes, it does fix the issue. Partial Nested Loop joins
are generated now. If I see any unexpected differences in the
estimated or actual costs, I will report that in the Parallel Append
thread. As far as Partition-wise join is concerned, this issue is
solved, because Partial nested loop join does get created.

>
> --
> Best Wishes,
> Ashutosh Bapat
> EnterpriseDB Corporation
> The Postgres Database Company



-- 
Thanks,
-Amit Khandekar
EnterpriseDB Corporation
The Postgres Database Company


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