Horton

Re: On disable_cost

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

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: David Rowley <dgrowleyml@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2024-05-06T20:10:44Z
Lists: pgsql-hackers 
Robert Haas <robertmhaas@gmail.com> writes:
> I'll look into this, unless you want to do it.

I have a draft patch already.  Need to add a test case.

> Incidentally, another thing I just noticed is that
> IsCurrentOfClause()'s test for (node->cvarno == rel->relid) is
> possibly dead code. At least, there are no examples in our test suite
> where it fails to hold. Which seems like it makes sense, because if it
> didn't, then how did the clause end up in baserestrictinfo? Maybe this
> is worth keeping as defensive coding, or maybe it should be changed to
> an Assert or something.

I wouldn't remove it, but maybe an Assert is good enough.  The tests
on Vars' varno should be equally pointless no?

			regards, tom lane

Commits

  1. Doc: add detail about EXPLAIN's "Disabled" property

  2. Adjust EXPLAIN's output for disabled nodes

  3. Fix order of parameters in a cost_sort call

  4. Show number of disabled nodes in EXPLAIN ANALYZE output.

  5. Treat number of disabled nodes in a path as a separate cost metric.

  6. Remove grotty use of disable_cost for TID scan plans.