diff --git a/database/migrations/2024_05_25_000000_add_source_index_to_polylines.php b/database/migrations/2024_05_25_000000_add_source_index_to_polylines.php
new file mode 100644
index 000000000..1400518f6
--- /dev/null
+++ b/database/migrations/2024_05_25_000000_add_source_index_to_polylines.php
@@ -0,0 +1,20 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void {
+        Schema::table('poly_lines', static function(Blueprint $table) {
+            $table->index(['source']);
+        });
+    }
+
+    public function down(): void {
+        Schema::table('poly_lines', static function(Blueprint $table) {
+            $table->dropIndex(['source']);
+        });
+    }
+};