Re: Parallel copy - Mailing list pgsql-hackers

From Amit Kapila
Subject Re: Parallel copy
Date
Msg-id CAA4eK1LQPxULxw8JpucX0PwzQQRk=q4jG32cU1us2+-mtzZUQg@mail.gmail.com
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In response to Re: Parallel copy  (Ashutosh Sharma <ashu.coek88@gmail.com>)
Responses Re: Parallel copy
List pgsql-hackers
On Mon, Jun 15, 2020 at 7:41 PM Ashutosh Sharma <ashu.coek88@gmail.com> wrote:
>
> Thanks Amit for the clarifications. Regarding partitioned table, one of the question was - if we are loading data
intoa partitioned table using COPY command, then the input file would contain tuples for different tables (partitions)
unlikethe normal table case where all the tuples in the input file would belong to the same table. So, in such a case,
howare we going to accumulate tuples into the DSM? I mean will the leader process check which tuple needs to be routed
towhich partition and accordingly accumulate them into the DSM. For e.g. let's say in the input data file we have 10
tupleswhere the 1st tuple belongs to partition1, 2nd belongs to partition2 and likewise. So, in such cases, will the
leaderprocess accumulate all the tuples belonging to partition1 into one DSM and tuples belonging to partition2 into
someother DSM and assign them to the worker process or we have taken some other approach to handle this scenario? 
>

No, all the tuples (for all partitions) will be accumulated in a
single DSM and the workers/leader will route the tuple to an
appropriate partition.

> Further, I haven't got much time to look into the links that you have shared in your previous response. Will have a
lookinto those and will also slowly start looking into the patches  as and when I get some time. Thank you. 
>

Yeah, it will be good if you go through all the emails once because
most of the decisions (and design) in the patch is supposed to be
based on the discussion in this thread.

Note - Please don't top post, try to give inline replies.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com



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