Add comment that ec_relids excludes "child" EquivalenceClass members.

This was already documented a few lines further down, but the comment
just beside the field declaration could be misleading.  Per gripe
from Kyotaro Horiguchi.

diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 8aa40d0ef019b5ff16fff3b07a512fa54f1089c5..c607b36e3a715a11d3021be8d49c8ccb466d3bb8 100644 (file)
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -585,7 +585,8 @@ typedef struct EquivalenceClass
        List       *ec_members;         /* list of EquivalenceMembers */
        List       *ec_sources;         /* list of generating RestrictInfos */
        List       *ec_derives;         /* list of derived RestrictInfos */
-       Relids          ec_relids;              /* all relids appearing in ec_members */
+       Relids          ec_relids;              /* all relids appearing in ec_members, except
+                                                                * for child members (see below) */
        bool            ec_has_const;   /* any pseudoconstants in ec_members? */
        bool            ec_has_volatile;        /* the (sole) member is a volatile expr */
        bool            ec_below_outer_join;    /* equivalence applies below an OJ */