Fixed segmentation fault with COUNT - fixes #9

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

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

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;

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;

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;