Is it better to execute many sql commands with one connection, or reconnect every time?

Question

Here\'s my test code, which seems to suggest that it\'s better to connect multiple times instead of connecting just once.

Am I doing something wrong?

Answer 1

Since .NET reuses connections ("connection pooling"), there is not much overhead in creating a new instance of DbConnection several times in a row. ADO.NET will just reuse the connection under the hood. That's why it's good you are disposing the SqlConnection object each time, telling .NET that it can return it to the pool.

You can, however, increase performance of multiple inserts by using ADO.NET batching. In that case you can easily have several thousands of inserts per second. If performance is critical, you can even consider using SQLBulkCopy.

Also, your first pair of results is quite strange: 30s for 100 inserts?