RE: Parallel INSERT (INTO ... SELECT ...)

From: "Hou, Zhijie" <houzj(dot)fnst(at)cn(dot)fujitsu(dot)com>
To: Greg Nancarrow <gregn4422(at)gmail(dot)com>
Cc: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Antonin Houska <ah(at)cybertec(dot)at>, Dilip Kumar <dilipbalaut(at)gmail(dot)com>, vignesh C <vignesh21(at)gmail(dot)com>, "Bharath Rupireddy" <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: RE: Parallel INSERT (INTO ... SELECT ...)
Date: 2021-01-21 09:18:23
Message-ID: c8b1746ab6f7424c9e0c859d2ac43a1a@G08CNEXMBPEKD05.g08.fujitsu.local
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> > So I think we're saying that if the target table is a foreign table or
> > temporary table, it can be regarded as PARALLEL_RESTRICTED, right?
> >
>
> Yes
>
> IMO, PARALLEL_RESTRICTED currently enable parallel select but disable
> parallel insert.
> So, the INSERT only happen in leader worker which seems safe to insert into
> tempory/foreigh table.
>
> In addition, there are some other restriction about parallel select which
> seems can be removed:
>
> 1.- Target table has a parallel-unsafe trigger, index expression, column
> default
> expression or check constraint
> 2.- Target table is a partitioned table with a parallel-unsafe partition
> key
> expression or support function
>
> If the Insert's target table is the type listed above, Is there some reasons
> why we can not support parallel select ?
> It seems only leader worker will execute the trigger and key-experssion
> which seems safe.
> (If I miss something about it, please let me know)

So Sorry, please ignore the above, I think of something wrong.

Best regards,
houzj

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