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Update wording in optimizer/README for EquivalenceClasses

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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
This commit is contained in:
David Rowley 2025-04-10 17:33:58 +12:00
parent d438515c29
commit d7c04db27a
1 changed files with 1 additions and 1 deletions
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src/backend/optimizer/README
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@ -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 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 affect the class's overall properties at all. They are kept only to
simplify matching of child-relation expressions to EquivalenceClasses. 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 PathKeys