[#12048] Add composite index for data migration

src/client/java/teammates/client/scripts/sql/IndexCourseFields.java

@@ -0,0 +1,37 @@
+package teammates.client.scripts.sql;
+
+import com.googlecode.objectify.cmd.Query;
+
+import teammates.client.scripts.DataMigrationEntitiesBaseScript;
+import teammates.storage.entity.Course;
+
+/**
+ * Index the newly-indexable fields of courses.
+ */
+public class IndexCourseFields extends DataMigrationEntitiesBaseScript<Course> {
+
+    public static void main(String[] args) {
+        new IndexCourseFields().doOperationRemotely();
+    }
+
+    @Override
+    protected Query<Course> getFilterQuery() {
+        return ofy().load().type(Course.class);
+    }
+
+    @Override
+    protected boolean isPreview() {
+        return true;
+    }
+
+    @Override
+    protected boolean isMigrationNeeded(Course course) {
+        return true;
+    }
+
+    @Override
+    protected void migrateEntity(Course course) {
+        // Save without any update; this will build the previously non-existing indexes
+        saveEntityDeferred(course);
+    }
+}

src/main/appengine/index.yaml

@@ -93,3 +93,15 @@ indexes:
     name: targetUser
   - direction: asc
     name: endTime
+- kind: Course
+  properties:
+  - direction: asc
+    name: isMigrated
+  - direction: asc
+    name: createdAt
+- kind: Course
+  properties:
+  - direction: asc
+    name: isMigrated
+  - direction: desc
+    name: createdAt