SharePoint 2013 Search : KQL vs FQL

In SharePoint 2013 KQL statements are translated to FQL before being executed. FQL has some tricks up it sleeve compared to the polished KQL counterpart.

FQL has even more operators, some of them listed below:

• starts-with
• ends-width
• count
• andnot
• range
• xrank
• near
• onear

A notable difference between KQL and FQL is the query syntax. Where KQL typically writes

exp OPERATOR exp OPERATOR exp

FQL uses a nested syntax

OPERATOR(OPERATOR(exp,exp),OPERATOR(exp,exp))

Operators can also be combined in different ways, and you may achieve the same result with different ways of writing a query.

KQL	FQL
foo OR bar	or(foo,bar)` string(“foo bar”, mode=”or”)
title="foo bar” title="zoo animal”	or(title:equals(“foo bar”),title:equals(“zoo animal”)) title:equals(or(“foo bar”,”zoo animal”))
id=1 id=3 id=4 id=10 id=12	id:int(“1 3 4 10 12″, mode=”or”)

The FQL operators most useful are starts-with and ends-with which can be used to find matching terms at the start and end of a field. You cannot do wildcard matches with starts-with/ends-with, only term based matching. KQL supports equals (=) and contains (:), but no matching at the start or end. You would typically use this against a managed property like a phone number: 555-1234

• phonenumber:starts-with(“555”)
• phonenumber:ends-with(“1234”)

Query on dates
Another useful scenario is when you want to filter on dates with a higher resolution than day. KQL will disregard any time portion of a date query while FQL will honor it. The sample below will return all documents produced after 12:35:57GMT.

write:range(2014-12-15T12:35:57.0000000Z,max,from=”gt”)

Querying using FQL
If you want to run a query using FQL you either have to use an FQL enables result source, where you on your REST or SSOM query set enableFQL to true. As far as I know you cannot do this using CSOM.

The easier and perhaps better alternative is to write your FQL statements as refinement filters. Refiner statements are by default sent over as FQL filters and enables a very powerful query feature by combining KQL and FQL in the same query. Note that FQL sent in the refinement part will not be part of the ranked expression – except with explicit XRANK statements.

If you ever find a scenario where KQL just don’t cut it, then take look at FQL and see if it provides the missing functionality you are looking for.