Horton

Re: Assertion failure with LEFT JOINs among >500 relations

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Onder Kalaci <onderk@microsoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2020-10-18T23:10:06Z
Lists: pgsql-hackers 
David Rowley <dgrowleyml@gmail.com> writes:
> On Sat, 17 Oct 2020 at 06:00, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>> I'm good with the v2 patch.

> Thanks a lot for having a look. I'll proceed in getting the v2 which I
> sent earlier into master.

> For the backbranches, I think I go with something more minimal in the
> form of adding:

TBH, I see no need to do anything in the back branches.  This is not
an issue for production usage.

			regards, tom lane

Commits

  1. Relax some asserts in merge join costing code

  2. Prevent overly large and NaN row estimates in relations

  3. Avoid a couple of zero-divide scenarios in the planner.

  4. Guard against incoming rowcount estimate of NaN in cost_mergejoin().

  5. When a relation has been proven empty by constraint exclusion, propagate that