metu.life-android/app/src/main/java/com/keylesspalace/tusky/db/AppDatabase.java

package com.keylesspalace.tusky.db;

import android.arch.persistence.db.SupportSQLiteDatabase;
import android.arch.persistence.room.Database;
import android.arch.persistence.room.RoomDatabase;
import android.arch.persistence.room.migration.Migration;

/**
 * DB version & declare DAO
 */

@Database(entities = {TootEntity.class}, version = 3, exportSchema = false)
public abstract class AppDatabase extends RoomDatabase {

    public abstract TootDao tootDao();

    public static final Migration MIGRATION_2_3 = new Migration(2, 3) {
        @Override
        public void migrate(SupportSQLiteDatabase database) {
            //this migration is necessary because of a change in the room library
            database.execSQL("CREATE TABLE TootEntity2 (uid INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL, text TEXT, urls TEXT, contentWarning TEXT);");

            database.execSQL("INSERT INTO TootEntity2 SELECT * FROM TootEntity;");
            database.execSQL("DROP TABLE TootEntity;");
            database.execSQL("ALTER TABLE TootEntity2 RENAME TO TootEntity;");

        }
    };

}