v20-only-part-3-0004-Optimize-auxiliary-index-handling.patch_

From 989bad4e1b0e1aea28a2c5db8ab93be2c2e5480a Mon Sep 17 00:00:00 2001
From: Mikhail Nikalayeu <mihailnikalayeu@gmail.com>
Date: Mon, 30 Dec 2024 16:37:12 +0100
Subject: [PATCH v20-only-part-3 4/5] Optimize auxiliary index handling
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Skip unnecessary computations for auxiliary indices by:
- in the index‐insert path, detect auxiliary indexes and bypass Datum value computation
- set indexUnchanged=false for auxiliary indices to avoid redundant checks

These optimizations reduce overhead during concurrent index operations.
---
 src/backend/catalog/index.c         | 11 +++++++++++
 src/backend/executor/execIndexing.c | 11 +++++++----
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/backend/catalog/index.c b/src/backend/catalog/index.c
index 07ca3dbc71f..2771434be1b 100644
--- a/src/backend/catalog/index.c
+++ b/src/backend/catalog/index.c
@@ -2915,6 +2915,17 @@ FormIndexDatum(IndexInfo *indexInfo,
 	ListCell   *indexpr_item;
 	int			i;
 
+	/* Auxiliary index does not need any values to be computed */
+	if (unlikely(indexInfo->ii_Auxiliary))
+	{
+		for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
+		{
+			values[i] = PointerGetDatum(NULL);
+			isnull[i] = true;
+		}
+		return;
+	}
+
 	if (indexInfo->ii_Expressions != NIL &&
 		indexInfo->ii_ExpressionsState == NIL)
 	{
diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c
index 499cba145dd..c8b51e2725c 100644
--- a/src/backend/executor/execIndexing.c
+++ b/src/backend/executor/execIndexing.c
@@ -440,11 +440,14 @@ ExecInsertIndexTuples(ResultRelInfo *resultRelInfo,
 		 * There's definitely going to be an index_insert() call for this
 		 * index.  If we're being called as part of an UPDATE statement,
 		 * consider if the 'indexUnchanged' = true hint should be passed.
+		 *
+		 * In case of auxiliary index always pass false as optimisation.
 		 */
-		indexUnchanged = update && index_unchanged_by_update(resultRelInfo,
-															 estate,
-															 indexInfo,
-															 indexRelation);
+		indexUnchanged = update && likely(!indexInfo->ii_Auxiliary) &&
+									index_unchanged_by_update(resultRelInfo,
+															  estate,
+															  indexInfo,
+															  indexRelation);
 
 		satisfiesConstraint =
 			index_insert(indexRelation, /* index relation */
-- 
2.43.0