Re: Possible documentation inaccuracy in optimizer README

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

From: Tom Lane <tgl@sss.pgh.pa.us>
To: David Rowley <dgrowleyml@gmail.com>
Cc: Zeyuan Hu <ferrishu3886@gmail.com>, pgsql-docs@postgresql.org
Date: 2025-04-09T02:33:52Z
Lists: pgsql-docs
David Rowley <dgrowleyml@gmail.com> writes:
> I don't think it'd hurt to mention that we're just ignoring the
> existence of ECs for this example.

Seems like a reasonable approach.

> -    (other possibilities will be excluded for lack of join clauses)
> +    (other possibilities will be excluded for lack of join clauses
> +    (technically, EquivalenceClasses do allow us to determine derived join
> +    clauses for this case, but we ignore that for the simplicity of this
> +    example))

Maybe better:

	Other possibilities will be excluded for lack of join clauses.
	(In reality, use of EquivalenceClasses would allow us to
	deduce additional join clauses that allow more join
	combinations, but here we ignore that to preserve the
	simplicity of this example.)

			regards, tom lane



Commits

  1. Doc: note that two examples in optimizer/README are oversimplified.