How do I optimize this query - sql

Question

Create table #tmptble(RuleId, SubjectId, RID, Date)
Insert into #tmptble(RuleId,SubjectId, RID, Date)
Select RuleTable.RuleId, RuleTable.SubjectId, KeyTable.RID, KeyTable.ParentId
FROM RuleTable INNER JOIN KeyTable
ON KeyTable.RID = RuleTable.RID
This query is very slow. I have an clustered index on RID on KeyTable, clustered index on RuleId on RuleTable, Unique non clustered index on RuleId+SubjectId on the RuleTable. (RuleTable is used in various other places)
In the above query if I introduce a where clause like
Insert into #tmptble(RuleId,SubjectId, RID, Date)
Select RuleTable.RuleId, RuleTable.SubjectId, KeyTable.RID, KeyTable.ParentId
FROM RuleTable INNER JOIN KeyTable
ON KeyTable.RID = RuleTable.RID
WHERE KeyTable.RID = #RID -- #RID is passed into the storedproc
the running time reduces by > 50%. But the problem is that I use the original table result without the WHERE clause in the following way
WITH ResourceTree AS
(
SELECT
#tmptble.RuleId AS [RuleId],
#tmptble.SubjectId AS [SubjectRecId],
#tmptble.RId AS [RId],
#tmptble.ParentID AS [ParentID]
FROM #tmptble WHERE #tmptble.SubjectId = #SubjectId
AND #tmptble.RId = #RId
UNION ALL
-- Recursive step
-- Note that the recursive step uses the results from original #tmptable
SELECT
#tmptble.RuleId AS [RuleId],
#tmptble.SubjectId AS [SubjectId],
#tmptble.RId AS [RId],
#tmptble.ParentID AS [ParentID]
FROM #tmptble INNER JOIN ResourceTree RT
ON RT.ParentID = #tmptble.RId
)
SELECT *
FROM ResourceTree
Is there a way to optimize this query? Any kind of suggestions regarding indexes or way recursion is done would be helpful

Answer 1

Possible this be helpful for you -
;WITH temp AS
(
SELECT
r.RuleId
, r.SubjectId
, r.RID
, k.ParentId
FROM (
SELECT r.*
FROM dbo.RuleTable r
WHERE r.RID = #RID
) r
JOIN dbo.KeyTable k ON k.RID = r.RID
)
, ResourceTree AS
(
SELECT
t.RuleId
, [SubjectRecId] = t.SubjectId
, t.RId
, t.ParentID
FROM temp t
WHERE t.SubjectId = #SubjectId
UNION ALL
SELECT
t.RuleId
, t.SubjectId
, t.RId
, t.ParentID
FROM temp t
WHERE EXISTS (
SELECT 1
FROM ResourceTree r
WHERE r.ParentID = t.RId
)
)
SELECT *
FROM ResourceTree