The new Multi-Value fields are causing me quite some headaches lately. Exporting to Excel does not work, showing in Content-Editor-Webparts does not work, SharePoint Designer does not understand them, and now there's an issue querying them trough the Search Engine…

The SDK describes Multi-valued (ARRAY) Comparisons in Windows SharePoint Services Search SQL Syntax, but when using it it returns an error. The problem lies in SharePoint not recognizing an Multi-Value Lookup as Multi-valued.

You can use the MetaData Property Mappings page to check whether an Site Column gets indexed as a Multi-Value column:

I used an out-of-the-box environment with SP1. I've made a Content Type and added/created some Site Columns of different Multi-Value types:
- Multi Choice field
- Multiline text field (I know, this is just a blob, but I wanted to be sure..)
- Multiline text field with unlimited length
- Multi-Value Lookup field
- Multi-Value Lookup field with unlimited length
- Multi-Value People field

Except for the Multi Choice field none of them gets recognized as a Multi-Value field. I even tried to create a piece of content based on the content type with Multiple selections made, before I let the Index server crawl the content and discover the new Site Columns. If it doesn't see it by then it never wil… So were stuck using LIKE operators, which will probably not do the performance any good.  

Anyone with the same experience or a workaround?