Subquery Performance - Non Unique Column in Where Clause - sql

Question

I have two tables
Table Jobs
[ID] [int] IDENTITY(1,1) NOT NULL,
[title] [varchar](150) NULL,
[description] [text] NULL
Table JobSkills
[id] [int] IDENTITY(1,1) NOT NULL,
[jobId] [int] NULL,
[skill] [varchar](150) NULL
Shown above partial list of columns.
For table JobSkills I have indexed jobId column, column skill is full text indexed.
I have a stored procedure to get the list of jobs. sort of like this.
Select totalItems
,Id,title
from
(
Select Row_Number() over(Order By
CASE WHEN #sortBy Is Not Null AND #sortBy='relevance'
THEN
SkillMatchRank
END DESC
,CASE WHEN #sortBy Is Not Null AND #sortBy='date' THEN CreateDate END DESC
) As rowNumber
,COUNT(*) OVER() as totalItems
,ID,createDate,title
from Jobs J
OUTER APPLY dbo.GetJobSkillMatchRank(J.ID,#searchKey) As SkillMatchRank
Where
--where conditions here
) tempData
where
rowNumber>=CASE WHEN #startIndex>0 AND #endIndex>0 THEN #startIndex ELSE rowNumber END
AND rowNumber<=CASE WHEN #startIndex>0 AND #endIndex>0 THEN #endIndex ELSE rowNumber END
I have created a inline table valued function to get the skill matching rank.
CREATE FUNCTION [dbo].[GetJobSkillMatchRank]
(
#jobId int,
#searchKey varchar(150)
)
RETURNS TABLE
AS
RETURN
(
select SUM(ISNULL(JS2.[Rank],0)) as rank
from FREETEXTTABLE(JobSkills,skill,#searchKey) JS2
Where JS2.[Key] in (Select ID from JobSkills Where jobId=#jobId)
)
GO
Problem
Query runs super slow, more then a minute.
My observation
For the table valued function if I set jobId=1 (I do have a job with id=1) then it performs super fast as desired.
I understand that jobId is not unique column on JobSkills table.
In this case how could I improve the performance???

Answer 1

UDFs are great in certain cases, but the execution plans don't get cached like sprocs do. If you try using another derived table instead of a function, the query might perform better.