An acknowledged FIM Best Practice is the regular rebuilding of the full text catalog for the FIM Service database, since this optimizes performance of FIM queries.  Without attention to maintaining this catalog you may find that you will get SQL timeouts occurring leading to failures in FIM requests.

The catalog for the FIMService database is named ftCatalog, and can be located using Microsoft SQL Server Management Studio on your FIM SQL host server under Databases/FIMService/Storage/Full Text Catalogs:

The rebuild of this catalog can be initiated by simply selecting Rebuild from the Properties menu of this object:

... and as you can see from this TechNet article there isn't much more to it ... except of course if you want to automate this!  Here's how:

  1. From SQL Server Management Studio, click on the above ftCatalog node in the tree view and select Properties from the right mouse menu:

    ... noting that the Population Status shows Idle in my screenshot above (during the population process this will instead show the progress with text such as "Populating catalog")
  2. From the page menu (top left) select Population Schedule:
  3. Click New:
  4. Give your schedule a name (I simply chose Nightly), specify a frequency (I have found Daily is appropriate ... since I have found performance degradation with FIM queries to occur within a 24 hour period), and click OK.
  5. Click on Properties again, select Population Schedule once more, select the schedule you created above, and then click on Edit.  The Jobs In Schedule button will now be enabled - click it to see how there is now a SQL Agent job that has been created to automate the rebuilding of the FIM ftCatalog:
For more information about Full-Text Index Properties please refer to this MSDN reference.

While the above settings have been in place in all environments for my current FIM site for several months now, we have yet to deploy to production ... at which point the above settings may be further refined.  However the above article is intended to explain HOW to set this feature up on your own FIM sites, and not necessarily WHAT you should be setting the properties to yourselves - this may vary from site to site based on a number of environmental considerations, and I recommend you experiment with these to arrive at the best option for your sites.