Asynchronous execution means running more than one query at the same time (from different SQL windows) or working with the application interface while the query (queries) still executing. To enable asynchronous execution, turn the corresponding option from SQL Queries section on.
Please note that not all databases allow to run database queries in parallel. If your database does not support that, you still will be able to run multiple SQL queries at the same time and work with Database Tour interface, but the database will process your queries successively.
Asynchronous query execution in PostgreSQL database:
Here, we are working with SQL text in SQL 1 window, while four other windows execute their queries.
One of them already finished successfully, another one finished with error, and two others are still in progress.
See also