v50-0020-clarify-step-no_equal.patch

From 59052a0beb3a7489b026dee2e812ae31db6858fb Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Tue, 23 Jun 2026 21:39:36 +0900
Subject: [PATCH v50 29/29] Clarify row pattern recognition comments on "step"
 and no_equal

Define "step" in isUnboundedStart()'s examples as the number of VARs in
one fully unrolled iteration of the group, and reword the RPRPattern
comment on why equal() support is suppressed: equal() routines are
generated only for parse/rewrite nodes, not plan nodes.  Comment-only.
---
 src/backend/optimizer/plan/rpr.c | 3 +++
 src/include/nodes/plannodes.h    | 7 ++++---
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/backend/optimizer/plan/rpr.c b/src/backend/optimizer/plan/rpr.c
index 1c59e8a70a0..fac3d7bcf38 100644
--- a/src/backend/optimizer/plan/rpr.c
+++ b/src/backend/optimizer/plan/rpr.c
@@ -1583,6 +1583,9 @@ isFixedLengthChildren(RPRPattern *pattern, RPRElemIdx idx, RPRDepth scopeDepth)
  *      This is equivalent to unrolling to {1,1} VARs, e.g., (A B B)+ C.
  *      All elements within the group get ABSORBABLE_BRANCH.
  *      Only the unbounded END gets ABSORBABLE (comparison point).
+ *
+ *      In the examples below, "step" is the number of VARs in one fully
+ *      unrolled iteration of the group (its fixed per-iteration length).
  *      Examples:
  *        (A B{2})+ C          - B{2} has min==max, step=3
  *        (A (B C){2} D)+ E    - nested {2} subgroup, step=6
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 7c4eacdf82d..2b37c8f226a 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -1284,9 +1284,10 @@ typedef struct RPRPattern
 {
 	/*
 	 * RPRPattern is a plan/exec-only node with arrays that need a
-	 * hand-written copy (custom_copy_equal), but it is never compared by
-	 * equal() -- it does not appear in parse/rewrite trees, and equal() has
-	 * no Plan-node routines -- so equal support is suppressed with no_equal.
+	 * hand-written copy (custom_copy_equal).  It is never compared with
+	 * equal(): equal() routines are generated only for parse/rewrite-level
+	 * nodes, not for plan nodes, so there is nothing to compare it against
+	 * and equal support is suppressed with no_equal.
 	 */
 	pg_node_attr(custom_copy_equal, custom_read_write, no_equal)
 
-- 
2.50.1 (Apple Git-155)