Android SQLite: should I use beginTransaction and endTransaction only at insert or both insert and read queries?

Question

ATM when I write to the SQLite in my android app, I do it this way:

try {
    for (User user: users) {
        ContentValues values = new ContentValues();
        databaseManager.database.beginTransaction();
        values.put("user_name", user.getName());
        values.put("user_email", user.getEmail());
        databaseManager.database.insert("users", null, values);
    }
    databaseManager.database.setTransactionSuccessful();
} catch (Exception ex) {
    ex.printStackTrace();
} finally {
    databaseManager.database.endTransaction();
}

But when I read from the DB, I dont use begin, setsuccessful and end:

Cursor cursor = databaseManager.database.rawQuery(SQLQueries.getUsers(), null);
if (cursor.moveToFirst()) {
    if (cursor!=null) {
        do {
            User user = new User();
            try {
                user.setName(cursor.getString(cursor.getColumnIndexOrThrow("user_name")));
                user.setEmail(cursor.getString(cursor.getColumnIndexOrThrow("user_email")));                        
            } catch (Exception ex) {
                ex.printStackTrace();
            }
            users.add(user);
        } while (cursor.moveToNext());
    }
}

if (cursor != null && !cursor.isClosed()) {
    cursor.close();
    cursor = null;
}

Should I add beginTransaction, setTransactionSuccessful and endTransaction to the read operations as well? Im pretty sure I shouldnt, but I need to be 100% on this one.

Answer 1

When you are not using explicit transactions, SQLite will automatically wrap a transaction around every statement.

When you write to the database, every insert/update/delete call is a single statement. If you are doing multiple such operations, you use transactions to avoid paying the transaction overhead for each of them.

A query (query or rawQuery) is a single statement, even if it returns multiple rows. Therefore, using a transaction around a single query does not make any difference. (If you have multiple queries, you could use a transaction to ensure that their results are consistent with each other even if another thread attempts to change the database between them.)