Horton

Re: parallelize queries containing initplans

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Amit Kapila <amit.kapila16@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Haribabu Kommi <kommi.haribabu@gmail.com>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-10-05T12:38:00Z
Lists: pgsql-hackers 
On Thu, Oct 5, 2017 at 5:52 AM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> Now, unless, I am missing something here, it won't be possible to
> detect params in such cases during forming of join rels and hence we
> need the tests in generate_gather_paths.  Let me know if I am missing
> something in this context or if you have any better ideas to make it
> work?

Hmm, in a case like this, I think we shouldn't need to detect it.  The
Var is perfectly parallel-safe, the problem is that we can't use a
not-safe plan for the inner rel.  I wonder why that's happening
here... is it a problem with your patch or an existing bug?

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

Commits

  1. Pass InitPlan values to workers via Gather (Merge).

  2. Track in the plan the types associated with PARAM_EXEC parameters.

  3. Force rescanning of parallel-aware scan nodes below a Gather[Merge].