fix lateral join group indexing

src/hnsw/hnsw_optimize_join.cpp

@@ -137,12 +137,12 @@ OperatorResultType PhysicalHNSWIndexJoin::Execute(ExecutionContext &context, Dat
 	for (idx_t batch_idx = 0; batch_idx < batch_count; batch_idx++, state.input_idx++) {
 
 		// Get the next batch
-		const auto rhs_vector_data = rhs_vector_ptr + batch_idx * rhs_vector_size;
+		const auto rhs_vector_data = rhs_vector_ptr + state.input_idx * rhs_vector_size;
 
 		// Scan the index for row ids
 		const auto match_count = hnsw_index.ExecuteMultiScan(*state.index_state, rhs_vector_data, limit);
 		for (idx_t i = 0; i < match_count; i++) {
-			state.match_sel.set_index(output_idx, batch_idx);
+			state.match_sel.set_index(output_idx, state.input_idx);
 			row_number_vector[output_idx] = i + 1; // Note: 1-indexed!
 			output_idx++;
 		}

test/sql/hnsw/hnsw_lateral_join_group_large.test

@@ -0,0 +1,114 @@
+require vss
+
+statement ok
+SELECT setseed(0.1337);
+
+statement ok
+CREATE TABLE queries (id INT, embedding FLOAT[3]);
+
+statement ok
+INSERT INTO queries SELECT i, [random(), random(), random()]::FLOAT[3] FROM range(1, 1000) as r(i);
+
+statement ok
+CREATE TABLE items (id INT, embedding FLOAT[3]);
+
+statement ok
+INSERT INTO items SELECT i, [random(), random(), random()]::FLOAT[3] FROM range(1, 1000) as r(i);
+
+
+# Sanity check, total cardinality
+query I
+SELECT COUNT(*)
+FROM queries, LATERAL (
+	SELECT
+		items.id as nbr,
+		array_distance(items.embedding, queries.embedding) as dist
+	FROM items
+	ORDER BY dist
+	LIMIT 3
+);
+----
+2997
+
+query I rowsort result_total
+SELECT COUNT(*)
+FROM queries, LATERAL (
+	SELECT
+		items.id as nbr,
+		array_distance(items.embedding, queries.embedding) as dist
+	FROM items
+	ORDER BY dist
+	LIMIT 3
+);
+----
+
+# Sanity check, groups of 3
+query I rowsort result_count
+SELECT count(*) FROM (
+	SELECT queries.id as id, any_value(nbr)
+	FROM queries, LATERAL (
+		SELECT
+			items.id as nbr,
+			array_distance(items.embedding, queries.embedding) as dist
+		FROM items
+		ORDER BY dist
+		LIMIT 3
+	) GROUP BY queries.id
+)
+----
+
+
+query II rowsort result_scan
+SELECT queries.id as id, list(nbr ORDER BY nbr) result_scan
+	FROM queries, LATERAL (
+		SELECT
+			items.id as nbr,
+			array_distance(items.embedding, queries.embedding) as dist
+		FROM items
+		ORDER BY dist
+		LIMIT 3
+	) GROUP BY queries.id
+----
+
+
+# Now create an index
+statement ok
+CREATE INDEX items_embedding_idx ON items USING hnsw(embedding);
+
+query I rowsort result_total
+SELECT COUNT(*)
+FROM queries, LATERAL (
+	SELECT
+		items.id as nbr,
+		array_distance(items.embedding, queries.embedding) as dist
+	FROM items
+	ORDER BY dist
+	LIMIT 3
+);
+----
+
+query I rowsort result_count
+SELECT count(*) FROM (
+	SELECT queries.id as id, any_value(nbr)
+	FROM queries, LATERAL (
+		SELECT
+			items.id as nbr,
+			array_distance(items.embedding, queries.embedding) as dist
+		FROM items
+		ORDER BY dist
+		LIMIT 3
+	) GROUP BY queries.id
+)
+----
+
+query II rowsort result_scan
+SELECT queries.id as id, list(nbr ORDER BY nbr)
+	FROM queries, LATERAL (
+		SELECT
+			items.id as nbr,
+			array_distance(items.embedding, queries.embedding) as dist
+		FROM items
+		ORDER BY dist
+		LIMIT 3
+	) GROUP BY queries.id
+----