From 57e6a01214f04446fde8f72c98369add33cf8829 Mon Sep 17 00:00:00 2001
From: Andrew Kane <andrew@ankane.org>
Date: Wed, 9 Jun 2021 03:13:22 -0700
Subject: [PATCH] Fixed segmentation fault with COUNT - fixes #9

---
 CHANGELOG.md                 |  4 ++++
 src/ivfflat.c                | 13 +++++++++++++
 src/ivfscan.c                |  4 ++++
 test/expected/ivfflat_l2.out |  6 ++++++
 test/sql/ivfflat_l2.sql      |  1 +
 5 files changed, 28 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f92b38b..79d2748 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.1.6 (unreleased)
+
+- Fixed segmentation fault with `COUNT`
+
 ## 0.1.5 (2021-05-25)
 
 - Reduced memory usage during index creation
diff --git a/src/ivfflat.c b/src/ivfflat.c
index 4192cfb..29b8248 100644
--- a/src/ivfflat.c
+++ b/src/ivfflat.c
@@ -51,6 +51,19 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	qinfos = deconstruct_indexquals(path);
 #endif
 
+	/* Never use index without order */
+	if (path->indexorderbys == NULL)
+	{
+		*indexStartupCost = 1.0e10;
+		*indexTotalCost = 1.0e10;
+		*indexSelectivity = 0;
+		*indexCorrelation = 0;
+#if PG_VERSION_NUM >= 100000
+		*indexPages = 0;
+#endif
+		return;
+	}
+
 	MemSet(&costs, 0, sizeof(costs));
 
 #if PG_VERSION_NUM >= 120000
diff --git a/src/ivfscan.c b/src/ivfscan.c
index 99dc0f3..7dfdf49 100644
--- a/src/ivfscan.c
+++ b/src/ivfscan.c
@@ -251,6 +251,10 @@ ivfflatgettuple(IndexScanDesc scan, ScanDirection dir)
 	{
 		Datum		value;
 
+		/* Safety check */
+		if (scan->orderByData == NULL)
+			elog(ERROR, "cannot scan ivfflat index without order");
+
 		/* No items will match if null */
 		if (scan->orderByData->sk_flags & SK_ISNULL)
 			return false;
diff --git a/test/expected/ivfflat_l2.out b/test/expected/ivfflat_l2.out
index 506cf48..449ea73 100644
--- a/test/expected/ivfflat_l2.out
+++ b/test/expected/ivfflat_l2.out
@@ -19,4 +19,10 @@ SELECT * FROM t ORDER BY val <-> (SELECT NULL::vector);
 -----
 (0 rows)
 
+SELECT COUNT(*) FROM t;
+ count 
+-------
+     5
+(1 row)
+
 DROP TABLE t;
diff --git a/test/sql/ivfflat_l2.sql b/test/sql/ivfflat_l2.sql
index 336434e..f4078a7 100644
--- a/test/sql/ivfflat_l2.sql
+++ b/test/sql/ivfflat_l2.sql
@@ -10,5 +10,6 @@ INSERT INTO t (val) VALUES ('[1,2,4]');
 
 SELECT * FROM t ORDER BY val <-> '[3,3,3]';
 SELECT * FROM t ORDER BY val <-> (SELECT NULL::vector);
+SELECT COUNT(*) FROM t;
 
 DROP TABLE t;