commit f458c90bff45ecae91fb55ef2b938af37d977af3
Author: Bruce Momjian <bruce@momjian.us>
Date:   Mon Sep 5 22:08:14 2011 -0400

    Add C comment about why we send cache invalidation messages for
    session-local objects.

diff --git a/src/backend/utils/cache/inval.c b/src/backend/utils/cache/inval.c
new file mode 100644
index 337fe64..98dc3ad
*** a/src/backend/utils/cache/inval.c
--- b/src/backend/utils/cache/inval.c
*************** ProcessCommittedInvalidationMessages(Sha
*** 812,817 ****
--- 812,821 ----
   * about CurrentCmdInvalidMsgs too, since those changes haven't touched
   * the caches yet.
   *
+  * We still send invalidation messages for session-local objects to other
+  * backends because, while other backends cannot see any tuples, they can
+  * drop tables that are session-local to another session.
+  * 
   * In any case, reset the various lists to empty.  We need not physically
   * free memory here, since TopTransactionContext is about to be emptied
   * anyway.