There may be a rare instance when the Query engine does not seem recognize the TADB when a user tries to run an expression.
This could happen, for example, if someone manually entered an expression directly into the database table instead of through the Query Engine or if someone directly changed the structure of the database.
If you cannot correct the problem any other way, you can use a Query Engine Reset feature.
Caution: The Query Engine reset tool should be used only as a last resort.
When you use the tool it:
Waits for any queries that are going on to stop first.
Puts all queries that have not yet started on hold.
Will stop until the last running query is done,
The Stop Queries will last until the longest currently running query finishes, which could require a substantial amount of time.
This is the issue that particularly requires your attention before you decide to go ahead.
Does the following when the last query is completed.
Reads the meta-data.
Re-reads the expressions out of the database.
Allows the queries to resume when the reset is complete.
Do the following to use the Reset tool.
Select Reset on the menu.
About the Query Engine