Update wording in optimizer/README for EquivalenceClasses

david-rowley · david-rowley · commit d7c04db27aeb · 2025-04-10T17:33:58.000+12:00
d69d45a 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
diff --git a/src/backend/optimizer/README b/src/backend/optimizer/README
@@ -902,7 +902,7 @@ contain the equivalent child-relation variables or expressions.  These
 members are *not* full-fledged members of the EquivalenceClass and do not
 affect the class's overall properties at all.  They are kept only to
 simplify matching of child-relation expressions to EquivalenceClasses.
-Most operations on EquivalenceClasses should ignore child members.
+Most operations on EquivalenceClasses needn't look at child members.
 
 
 PathKeys
