Horton

Re: pgsql: Support partition pruning at execution time

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Andrew Gierth <andrew@tao11.riddles.org.uk>, David Rowley <david.rowley@2ndquadrant.com>, pgsql-committers@lists.postgresql.org
Date: 2018-04-09T22:03:02Z
Lists: pgsql-hackers 
Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> I then noticed that support for nfiltered3 was incomplete; hence 0001.
> (I then noticed that nfiltered3 was added for MERGE.  It looks wrong to
> me.)

In that case, it's likely to go away when Simon reverts MERGE.  Suggest
you hold off committing until he's done so, as he probably already has
some conflicts to deal with and doesn't need another.

> Frankly, I don't like this.  I would rather have an instrument->ntuples2
> rather than these "divide this by nloops, sometimes" schizoid counters.
> This is already being misused by ON CONFLICT (see "other_path" in
> show_modifytable_info).  But it seems like a correct fix would require
> more code.

The question then becomes whether to put back nfiltered3, or to do
something more to your liking.  Think I'd vote for the latter.

			regards, tom lane

Commits

  1. Update Append's idea of first_partial_plan

  2. Fix IndexOnlyScan counter for heap fetches in parallel mode

  3. Fix incorrect logic for choosing the next Parallel Append subplan

  4. Minor comment updates

  5. Attempt to stabilize partition_prune test output.

  6. Support partition pruning at execution time