Update wording in optimizer/README for EquivalenceClasses
authorDavid Rowley <drowley@postgresql.org>
Thu, 10 Apr 2025 05:33:58 +0000 (17:33 +1200)
committerDavid Rowley <drowley@postgresql.org>
Thu, 10 Apr 2025 05:33:58 +0000 (17:33 +1200)
commitd7c04db27aeba1718d8059eae9a6e6a5eedc01b8
treeac8dbeb7e2b623ebc43e8ccff06a73ea7bf9eb86
parentd438515c29c3cc539c79292c040335804183ca3e
Update wording in optimizer/README for EquivalenceClasses

d69d45a5a changed how em_is_child members are stored in
EquivalenceClasses.  Children are no longer stored in the ec_members
list.  optimizer/README mentioned that most operations "should ignore
child members", but that felt a little untrue now since child members
are now stored in a separate place, they simply won't be found by the
normal means of looking (a foreach loop over ec_members), and if you don't
find them, there's technically no need to "ignore" them.

Here we tweak the wording slightly to reflect the new storage location
for child members.

Reported-by: Amit Langote <amitlangote09@gmail.com>
Author: Amit Langote <amitlangote09@gmail.com>
Author: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CA+HiwqE8v=EuAP_3F_A2xn8zWx+nG_etW_Fe_DvKO-Fkx=+DdQ@mail.gmail.com
src/backend/optimizer/README