Refiners are cool either if you use SharePoint Search or FAST, it’s not a question. I very like them, they give so much options and power to the end users.
But there’s a very common question around them: the deep and shallow behavior. As you know the definitions very well: FAST Search for SharePoint has deep refiners, that means each result in the result set is processed and used when calculating the refiners. And SharePoint Search uses shallow refiners, where the refiner values are calculated from the first 50 results only.
These definitions are easy, right? But let’s think a bit forward, and try to answer the question that pops up at almost every conference: Why some Refiner values are not visible when searching? Moreover: why they’re visible when running Query1 and hidden when running Query2?
For example: let’s say you have a lot of documents crawled, and you enter a query where the result set contains many-many items. Thousands, tens of thousands or even more.
Let’s say you have some Excel workbook in the result set that might be relevant for you, but this Excel file is not boosted in the result set at all, let’s say the first Excel result is on the 51th position (you have a lot of Word, PowerPoint, PDF, etc. files on the positions 1-50).
What happens if you use FAST Search? – As the refiners are deep, each result will be processed, so your Excel workbook. For example, in the Result Type refiner you’ll see all the Word, PowerPoint, PDF file types as well as the Excel. Easy way, you can click on the Excel refiner and you’ll get what you’re looking for immediately.
But what’s the case if you don’t have FAST Search, only the SharePoint one? – As the first 50 results is processed for the refiner calculation, your Excel workbook won’t be included. This means, the Result Type refiner displays the Word, PowerPoint, PDF refiners but doesn’t display the Excel at all, as your Excel file is not amongst the top results. You’ll see the Result Type refiner as if it there wasn’t any Excel result at all!
Conclusion: the difference between the shallow and deep refiners doesn’t seem to be so much important for the first sight. But you have to be aware there’s a huge difference in a real production environment as you and your users might have some “hidden” refiners, and sometimes it’s hard to understand why.
In other words, if a refiner value shows up on your Refinement Panel, that means:
- In case of FAST Search for SharePoint (deep refiner): There’s at least one item matching this refiner value in the whole result set. Exact number of the items match the refiner value is included.
- In case of SharePoint Search (shallow refiner): There’s at least one item matching this refiner value in the first 50 results.
If you cannot see a specific value on the Refiner Panel, that means:
- In case of FAST Search for SharePoint (deep refiner): There’s no result matching this refiner value at all.
- In case of SharePoint Search (shallow refiner): There’s no result matching this refiner in the first 50 results.