Query Monitor is one of the BEx monitor tools that enable to display and verify query correctness, test variants and additional query properties. To use it start RSRT transaction (you do not need BW front end).
I usually use Execute and Execute + Debug options. Execute + Debug option enable for example to check aggregates, set authorization breakpoints, run query with BI Accelerator, display SQL statement for the query and show BW statistics.
You may choose different query display format. BEX Analyser display format is by far the fastest and the simplest, List gives you additional query options and using HTML format you receive portal-like view.
You can also use the tool to check users' authorization to a query. To execute a query as another user startRSUDO transaction and choose a user and a query.
