A slightly misleading comment in GetNewObjectId()

From de4452ea50a4b51ca62f38faf4a95a3dc485edb8 Mon Sep 17 00:00:00 2001
From: Thomas Munro <thomas.munro@enterprisedb.com>
Date: Thu, 16 Aug 2018 16:00:28 +1200
Subject: [PATCH] Improve comment in GetNewObjectId().

The previous comment gave the impression that skipping OIDs before
FirstNormalObjectId was merely an optimization to avoid stepping over
collisions in a known populated range.  In fact other parts of
the system have been relying on this threshold to detect system-created
objects since commit 8e18d04d4da, so adjust the wording.

Thomas Munro
---
 src/backend/access/transam/varsup.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c
index 394843f7e9..cede579d73 100644
--- a/src/backend/access/transam/varsup.c
+++ b/src/backend/access/transam/varsup.c
@@ -476,11 +476,9 @@ GetNewObjectId(void)
 
 	/*
 	 * Check for wraparound of the OID counter.  We *must* not return 0
-	 * (InvalidOid); and as long as we have to check that, it seems a good
-	 * idea to skip over everything below FirstNormalObjectId too. (This
-	 * basically just avoids lots of collisions with bootstrap-assigned OIDs
-	 * right after a wrap occurs, so as to avoid a possibly large number of
-	 * iterations in GetNewOid.)  Note we are relying on unsigned comparison.
+	 * (InvalidOid), and in normal operation we mustn't return anything below
+	 * FirstNormalObjectId since that range is reserved for initdb (see
+	 * IsCatalogClass()).  Note we are relying on unsigned comparison.
 	 *
 	 * During initdb, we start the OID generator at FirstBootstrapObjectId, so
 	 * we only wrap if before that point when in bootstrap or standalone mode.
-- 
2.17.0