Multiple computers accessing Redshift database simultaneously

I am accessing a Redshift PostgreSQL database from the command line using the Database Connection Toolbox. My scripts involve reading values from the database, calculating new rows from them, then appending them to the database.

If multiple machines can be running these scripts at the same time, is there a way to lock out the database for the short period of time between a single computer's read and write commands? I tried using the SQL lock command, but that did not work.

[Jayaram Theegala]

Is there any reason why you are trying to lock the database? Generally the database itself handles synchronization of calls. Since there are some difference between PostgreSQL and Amazon's Redshift PostgreSQL, it is worth trying to do what you are trying to do on normal PostrgreSQL instance first.