From a156f6c7ae2aa8594623c62309551d7644108d4a Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Mon, 4 Dec 2023 15:00:32 -0800
Subject: [PATCH] Fixed invalid memory alloc request size error with HNSW -
 fixes #43

---
 CHANGELOG.md    | 1 +
 src/hnswbuild.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 21c9866..dc3589d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 ## 0.5.2 (unreleased)
 
 - Added support for on-disk parallel index builds for HNSW
+- Fixed `invalid memory alloc request size` error with HNSW
 
 ## 0.5.1 (2023-10-10)
 
diff --git a/src/hnswbuild.c b/src/hnswbuild.c
index ea7b889..8f4e0c7 100644
--- a/src/hnswbuild.c
+++ b/src/hnswbuild.c
@@ -56,6 +56,8 @@
 #define PARALLEL_KEY_HNSW_SHARED		UINT64CONST(0xA000000000000001)
 #define PARALLEL_KEY_QUERY_TEXT			UINT64CONST(0xA000000000000002)
 
+#define LIST_MAX_LENGTH ((1 << 26) - 1)
+
 /*
  * Create the metapage
  */
@@ -381,7 +383,7 @@ BuildCallback(Relation index, CALLBACK_ITEM_POINTER, Datum *values,
 	if (isnull[0])
 		return;
 
-	if (buildstate->memoryLeft <= 0)
+	if (buildstate->memoryLeft <= 0 || list_length(buildstate->elements) == LIST_MAX_LENGTH)
 	{
 		if (!buildstate->flushed)
 		{