FASTMaxNumberOfFilters

The case

You either run into this issue in the ULS log:
12/06/2012 13:34:27.23 w3wp.exe (0x2E30) 0x35D0 SharePoint Server Search Query dn1p Medium Filter category FASTMaxNumberOfFilters in the config is in wrong format.Input string was not in a correct format. 20932873-e591-4a68-ba36-7541401c2fea
...or you face a problem like this:

You're using FAST Search Server 2010 for SharePoint and you want to remove the limit of filters returned for a single refiner. Unfortunately you're unable to do so using the MaxNumberOfFilters property of the Category element in the configuration of the Refinement web part.

The problem

Somehow, FAST ignores the setting of MaxNumberOfFilters, or at least it ignores the value of '0' which, according to MSDN should tell SharePoint/FAST to return all filters, and not just a maximum of n.

The solution

There appears to be an undocumented attribute to the Category element called FASTMaxNumberOfFilters. I don't know why this isn't documented, but if you're using FAST it's the one to use instead of MaxNumberOfFilters. I came across this fact when I wanted my refiner to show all available filters (over 500) and it was somehow capped at 100, even though I had MaxNumberOfFilters set to 0. I had several ULS Log-errors stating that FASTMaxNumberOfFilters was not provided in the correct format, which triggered me to look further into this.
Setting FASTMaxNumberOfFilters to 0 won't be interpreted as "show all". Instead, you have to provide a positive number. In my case, I used 10000 and after that I correctly got my 500+ values instead of 100.

Example:

<Category Title="Sources" Description="The source of the document" Type="Microsoft.Office.Server.Search.WebControls.ManagedPropertyFilterGenerator" MetadataThreshold="1" NumberOfFiltersToDisplay="0" MaxNumberOfFilters="0" FASTMaxNumberOfFilters="10000" ShowMoreLink="True" MappedProperty="contentsource" MoreLinkText="show more" LessLinkText="show less" ShowCounts="Count" />

Remove crawled properties in FAST

Unfortunately, there's no PowerShell-command to delete/remove a single crawled property in FAST (nor is there one in SharePoint, as is stated by Corey Roth). In most cases, there's no need for such a command. However, when you're "experimenting" in a development environment, the list of debug/test/dummy crawled properties might become very long and the need to clean up the place might arise. It would've been nice if Microsoft offered the Remove-FASTSearchMetadataCrawledProperty command, in addition to the already available Get-, New-, Set- commands, but sadly, we'll have to do without this.

There is, however, a way to get rid of all unused/unmapped crawled properties all at once. You can either do this through the UI in Central Administration. Just go to your FAST Query Service Application > FAST Search Administration > Crawled Property Categories > [category-that-needs-cleaning] > Edit Category > Check "Delete all unmapped crawled properties" > Hit OK:

If you're more into scripting your configuration/deployment, there's also a nice way to do this through PowerShell. Just start up your FAST Search Server 2010 for SharePoint PowerShell window and run:

$category = Get-FASTSearchMetadataCategory -Name "[category-that-needs-cleaning]"
$category.DeleteUnmappedProperties()

FAST Search Server 2010 for SharePoint versions/build numbers

I couldn't find a nice short list of FAST Search versions/build numbers elsewhere so decided to write it down myself.

These are the different build numbers that are available for FAST Search Server 2010 for SharePoint (UPDATED 2013-02-13):

Build number	Description	Information	Download
14.0.4763.1000	RTM
14.0.5128.5001	October 2010 CU	KB2449730	Download
14.0.5136.5000	February 2011 CU	KB2504136	Download
14.0.6029.1000	Service Pack 1	KB2460039	Download
14.0.6109.5000	August 2011 CU	KB2553040	Download
14.0.6117.5002	February 2012 CU	KB2597131	Download
14.0.6120.5000	April 2012 CU	KB2598329	Download
14.0.6126.5000	August 2012 CU	KB2687489	Download

To check the installed version of FAST Search, go to "Programs and Features" and look for the "Microsoft FAST Search Server 2010 for SharePoint":