Re: parallel joins, and better parallel explain

From: Robert Haas <robertmhaas(at)gmail(dot)com>
To: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
Cc: "pgsql-hackers(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: parallel joins, and better parallel explain
Date: 2015-12-15 14:01:52
Message-ID: CA+Tgmoaz8EYCY=vxfrpc1jPdSzMYrk7M2q5dBjy1sD2KwZs+hg@mail.gmail.com
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On Mon, Dec 14, 2015 at 8:38 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> set enable_hashjoin=off;
> set enable_mergejoin=off;

[ ... ]

> Now here the point to observe is that non-parallel case uses both less
> Execution time and Planning time to complete the statement. There
> is a considerable increase in planning time without any benefit in
> execution.

So, you forced the query planner to give you a bad plan, and then
you're complaining that the plan is bad? That's not a very surprising
result.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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