From 4817be41a812df933f0a461609c6d38f35179aa4 Mon Sep 17 00:00:00 2001
From: Henson Choi <assam258@gmail.com>
Date: Mon, 1 Jun 2026 12:08:50 +0900
Subject: [PATCH 31/68] Rename the AST-level prefix/suffix rewrite from
 "absorption" to "merging"

"absorption" now refers only to the runtime context-equivalence collapse.
The Phase-1 AST rewrite in mergeGroupPrefixSuffix is renamed "prefix/suffix
merging" to match the sibling "consecutive variable / group / ALT merging"
rewrites.  Per the naming discussion with Tatsuo Ishii.
---
 src/backend/executor/README.rpr  |  2 +-
 src/backend/optimizer/plan/rpr.c | 17 ++++++++---------
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/src/backend/executor/README.rpr b/src/backend/executor/README.rpr
index 26c1a1ea236..449bf051153 100644
--- a/src/backend/executor/README.rpr
+++ b/src/backend/executor/README.rpr
@@ -221,7 +221,7 @@ applied:
   (d) Consecutive ALT merging: Merge repeated identical ALT nodes
       (A | B) (A | B) (A | B) -> (A | B){3}
 
-  (e) Prefix/suffix absorption: Absorb identical sequences before/after
+  (e) Prefix/suffix merging: Merge identical sequences before/after
       a group
       A B (A B)+ -> (A B){2,INF}
 
diff --git a/src/backend/optimizer/plan/rpr.c b/src/backend/optimizer/plan/rpr.c
index c65681463b3..2a1d665c7ee 100644
--- a/src/backend/optimizer/plan/rpr.c
+++ b/src/backend/optimizer/plan/rpr.c
@@ -480,7 +480,7 @@ mergeConsecutiveAlts(List *children)
  *		Merge sequence prefix/suffix into GROUP with matching children.
  *
  * When a GROUP's children appear as a prefix before and/or suffix after
- * the GROUP in a SEQ, absorb them by incrementing the GROUP's quantifier.
+ * the GROUP in a SEQ, merge them by incrementing the GROUP's quantifier.
  * This runs iteratively: A B A B (A B)+ A B -> (A B){5,}.
  *
  * Algorithm:
@@ -503,15 +503,15 @@ mergeGroupPrefixSuffix(List *children)
 	List	   *result = NIL;
 	int			numChildren = list_length(children);
 	int			i;
-	int			skipUntil = -1; /* skip suffix elements already absorbed */
+	int			skipUntil = -1; /* skip suffix elements already merged */
 
 	for (i = 0; i < numChildren; i++)
 	{
 		RPRPatternNode *child = (RPRPatternNode *) list_nth(children, i);
 
 		/*
-		 * The suffix absorption logic below adjusts i to skip absorbed
-		 * elements, ensuring we never revisit them. Verify this invariant.
+		 * The suffix merge logic below adjusts i to skip merged elements,
+		 * ensuring we never revisit them. Verify this invariant.
 		 */
 		Assert(i >= skipUntil);
 
@@ -543,7 +543,7 @@ mergeGroupPrefixSuffix(List *children)
 			groupChildCount = list_length(groupContent);
 
 			/*
-			 * PREFIX MERGE: Check if preceding elements match. Keep absorbing
+			 * PREFIX MERGE: Check if preceding elements match. Keep merging
 			 * as long as we have matching prefixes.
 			 */
 			while (prefixLen >= groupChildCount && groupChildCount > 0)
@@ -592,7 +592,7 @@ mergeGroupPrefixSuffix(List *children)
 			}
 
 			/*
-			 * SUFFIX MERGE: Check if following elements match. Keep absorbing
+			 * SUFFIX MERGE: Check if following elements match. Keep merging
 			 * as long as we have matching suffixes.
 			 */
 			while (i + groupChildCount < numChildren && groupChildCount > 0)
@@ -623,7 +623,7 @@ mergeGroupPrefixSuffix(List *children)
 					 child->max < RPR_QUANTITY_INF - 1))
 				{
 					/*
-					 * Match! Absorb suffix by incrementing quantifier and
+					 * Match! Merge suffix by incrementing quantifier and
 					 * skipping.
 					 */
 					child->min += 1;
@@ -632,8 +632,7 @@ mergeGroupPrefixSuffix(List *children)
 					skipUntil = suffixStart + groupChildCount;
 
 					/*
-					 * Update i to continue suffix check after absorbed
-					 * elements
+					 * Update i to continue suffix check after merged elements
 					 */
 					i = skipUntil - 1;
 				}
-- 
2.50.1 (Apple Git-155)