You may have read the following article and wondered "Which properties are included in the set of DEFAULTPROPERTIES, and how might I customize that set?" I have, and few customers of mine have as well (Hi Ben, Hi John!)
Best Practices: Writing SQL Syntax Queries for Relevant Results in Enterprise Search
http://msdn2.microsoft.com/en-us/library/bb219479.aspx
Also, by the way, it is my understanding that when you use Keyword Query Syntax that your freetext search terms are evaluated against only the DEFAULTPROPERTIES, so controlling which properties are part of this set can be important if you make extensive use of Managed metadata properties.
I've never found a good explanation of where DEFAULTPROPERTIES come from so I did a little digging on the topic and here is what my contact in Redmond was able to tell me:
- Any Managed Property with a non-zero weight is included in the definition of DEFAULTPROPERTIES, therefore any Managed Property accessible via the SharePoint Object Model* can be included in the list of DEFAULTPROPERTIES by setting its weight to a non-zero value.
- (updated 11/27/2008 - thanks to Nick!) In addition to setting the weight of the Managed Property, the Crawled Property that is mapped to the Managed Property must also have the “Include values for this property in the search index” check box set on.
- The property weight in MOSS is defined as part of a Managed Property (in contrast to SPS 2003 and prior, when weights were applied in the query). However, the configuration setting is not surfaced in the SSP admin UI for managed properties. The MOSS product developers invested a lot of research effort into tuning the weight values in order to optimize the relevancy of search results, and making changes can have unforeseen negative impacts on the quality of search results, but should you need to do it, the weights can be changed using the search objects that are available in the SharePoint Object Model: http://msdn2.microsoft.com/en-us/library/ms553069.aspx
Since you won't know what weight value will generate the best results for your scenario, start out by setting the weight to 1.0. Then conduct testing against your real data using real queries gathered from your user community. Gather user feedback to tune the weight value up or down. Note that each time you change a weight value you need to recycle the Office SharePoint Search service on your query server(s) to have it take effect.
*There are a few Managed properties which are integral to MOSS and cannot be configured. These are hidden via the object model.
The default set of DEFAULTPROPERTIES is comprised of the following non-zero weight managed properties:
- AnchorText (Hidden)
- Author
- Contents (Hidden)
- Filename
- Generated Title (Hidden)
- Title