One important thing to understand is that there is no data in a catalog. Think of a catalog as a road map to the data. The catalog contains the location of the database and the fields associated with the database. Whenever the database location changes, or fields associated with the database change, your catalog may need to be updated so that you can create successful queries against the database. Whenever ACS makes a change to a data warehouse database, the master Impromptu catalog is changed if it is necessary.
Every user is set up to use a distributed version of the master catalog.
If there are changes, your catalog is updated. Local modifications to your personal catalogs, such as customized filters and calculated fields will not be altered. When you have a catalog open, you can go to Catalog, Properties to see where your catalog looks for your master catalog. Personal catalogs are typically located on the 'c' drive or a server drive in a directory called EUR with subdirectories for the data families. You always work with your personal catalogs.