Prevent invalidation of paged messages by folder updates

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

@@ -54,7 +54,7 @@ import io.requery.android.database.sqlite.RequerySQLiteOpenHelperFactory;
 // https://developer.android.com/topic/libraries/architecture/room.html
 
 @Database(
-        version = 85,
+        version = 86,
         entities = {
                 EntityIdentity.class,
                 EntityAccount.class,
@@ -66,6 +66,9 @@ import io.requery.android.database.sqlite.RequerySQLiteOpenHelperFactory;
                 EntityAnswer.class,
                 EntityRule.class,
                 EntityLog.class
+        },
+        views = {
+                EntityFolderView.class
         }
 )
 
@@ -852,6 +855,13 @@ public abstract class DB extends RoomDatabase {
                         db.execSQL("UPDATE attachment SET size = NULL WHERE size = 0");
                     }
                 })
+                .addMigrations(new Migration(85, 86) {
+                    @Override
+                    public void migrate(SupportSQLiteDatabase db) {
+                        Log.i("DB migration from version " + startVersion + " to " + endVersion);
+                        db.execSQL("CREATE VIEW `folderview` AS SELECT id, account, name, type, display, unified FROM folder");
+                    }
+                })
                 .build();
     }