From 309fa94c055c361de3c7142560b039f8d90551a3 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Thu, 10 Aug 2023 08:52:45 -0700
Subject: [PATCH] Improved performance for duplicates

---
 src/hnswbuild.c | 15 +++++++++------
 src/hnswutils.c |  1 -
 2 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/hnswbuild.c b/src/hnswbuild.c
index 1073cc8..1a8ff7b 100644
--- a/src/hnswbuild.c
+++ b/src/hnswbuild.c
@@ -290,14 +290,17 @@ InsertTuple(Relation index, Datum *values, HnswElement element, HnswBuildState *
 	/* Insert element in graph */
 	*dup = HnswInsertElement(element, entryPoint, NULL, procinfo, collation, m, efConstruction, false);
 
-	/* Update neighbors */
-	for (int lc = element->level; lc >= 0; lc--)
+	if (*dup == NULL)
 	{
-		int			lm = HnswGetLayerM(m, lc);
-		HnswNeighborArray *neighbors = &element->neighbors[lc];
+		/* Update neighbors */
+		for (int lc = element->level; lc >= 0; lc--)
+		{
+			int			lm = HnswGetLayerM(m, lc);
+			HnswNeighborArray *neighbors = &element->neighbors[lc];
 
-		for (int i = 0; i < neighbors->length; i++)
-			HnswUpdateConnection(element, &neighbors->items[i], lm, lc, NULL, NULL, procinfo, collation);
+			for (int i = 0; i < neighbors->length; i++)
+				HnswUpdateConnection(element, &neighbors->items[i], lm, lc, NULL, NULL, procinfo, collation);
+		}
 	}
 
 	/* Update entry point if needed */
diff --git a/src/hnswutils.c b/src/hnswutils.c
index f1f3a55..2f69252 100644
--- a/src/hnswutils.c
+++ b/src/hnswutils.c
@@ -942,7 +942,6 @@ HnswInsertElement(HnswElement element, HnswElement entryPoint, Relation index, F
 	}
 
 	/* Look for duplicates */
-	/* This must come last, since duplicate updates can fail */
 	if (level >= 0 && !vacuuming)
 	{
 		dup = HnswFindDuplicate(element);