Database file is inexplicably locked during SQLite commit

Question

I\'m performing a large number of INSERTS to a SQLite database. I\'m using just one thread. I batch the writes to improve performance and have a bit of security in case of

Answer 1

It looks like you failed to link the command with the transaction you've created. Instead of:

using (SQLiteCommand command = conn.CreateCommand())

You should use:

using (SQLiteCommand command = new SQLiteCommand("", conn, trans))

Or you can set its Transaction property after its construction.

While we are at it - your handling of failures is incorrect:

The command's ExecuteNonQuery method can also fail and you are not really protected. You should change the code to something like:

   public void Commit()
    {
        using (SQLiteConnection conn = new SQLiteConnection(this.connString))
        {
            conn.Open();
            SQLiteTransaction trans = conn.BeginTransaction();
            try
            {
                using (SQLiteCommand command = conn.CreateCommand())
                {
                    command.Transaction = trans; // Now the command is linked to the transaction and don't try to create a new one (which is probably why your database gets locked)
                    command.CommandText = "INSERT OR IGNORE INTO [MY_TABLE] (col1, col2) VALUES (?,?)";

                    command.Parameters.Add(this.col1Param);
                    command.Parameters.Add(this.col2Param);

                    foreach (Data o in this.dataTemp)
                    {
                        this.col1Param.Value = o.Col1Prop;
                        this. col2Param.Value = o.Col2Prop;

                        command.ExecuteNonQuery();
                    }
                }

                trans.Commit();
            }
            catch (SQLiteException ex)
            {
                // You need to rollback in case something wrong happened in command.ExecuteNonQuery() ...
                trans.Rollback();
                throw;
            }
        }
    }

Another thing is that you don't need to cache anything in memory. You can depend on SQLite journaling mechanism for storing incomplete transaction state.