Added index on subject, cleanup

app/src/main/java/eu/faircode/email/DB.java

@@ -49,7 +49,7 @@ import io.requery.android.database.sqlite.RequerySQLiteOpenHelperFactory;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 49,
+        version = 50,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -537,6 +537,15 @@ public abstract class DB extends RoomDatabase {
                         db.execSQL("CREATE INDEX `index_operation_name` ON `operation` (`name`)");
                     }
                 })
+                .addMigrations(new Migration(49, 50) {
+                    @Override
+                    public void migrate(SupportSQLiteDatabase db) {
+                        Log.i("DB migration from version " + startVersion + " to " + endVersion);
+                        db.execSQL("DROP INDEX `index_message_replying`");
+                        db.execSQL("DROP INDEX `index_message_forwarding`");
+                        db.execSQL("CREATE INDEX `index_message_subject` ON `message` (`subject`)");
+                    }
+                })
                 .build();
     }
 

app/src/main/java/eu/faircode/email/EntityMessage.java

@@ -57,13 +57,12 @@ import static androidx.room.ForeignKey.SET_NULL;
                 @Index(value = {"account"}),
                 @Index(value = {"folder"}),
                 @Index(value = {"identity"}),
-                @Index(value = {"replying"}),
-                @Index(value = {"forwarding"}),
                 @Index(value = {"folder", "uid"}, unique = true),
                 @Index(value = {"msgid", "folder"}, unique = true),
                 @Index(value = {"thread"}),
                 @Index(value = {"sender"}),
                 @Index(value = {"received"}),
+                @Index(value = {"subject"}),
                 @Index(value = {"ui_seen"}),
                 @Index(value = {"ui_flagged"}),
                 @Index(value = {"ui_hide"}),