remove id pk from follows, use composite index

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "RSpec - active spec file only",
+      "type": "Ruby",
+      "request": "launch",
+      "program": "${workspaceRoot}/bin/rspec",
+      "args": ["-I", "${workspaceRoot}", "${file}"],
+      "showDebuggerOutput": true
+    }
+  ]
+}