Re: SELECT statement returns in 10seconds, but INSERT/CREATE TABLE AS with same SELECT takes 7 minutes

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Vladimir Ryabtsev <greatvovan(at)gmail(dot)com>
Cc: ranade(at)nodalexchange(dot)com, pgsql-performance(at)postgresql(dot)org
Subject: Re: SELECT statement returns in 10seconds, but INSERT/CREATE TABLE AS with same SELECT takes 7 minutes
Date: 2018-09-27 20:41:29
Message-ID: 22616.1538080889@sss.pgh.pa.us
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Vladimir Ryabtsev <greatvovan(at)gmail(dot)com> writes:
>> The reason for the plan shape difference is probably that the bare SELECT
>> is allowed to use parallelism while INSERT/SELECT isn't.

> In case parallelism is used, should it report in the plan as something like
> "workers planned: N"?

It did --- see the Gather node.

regards, tom lane

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