CRM 2011 EmailHashBase

Question

I have just upgraded to CRM 2011 from 4.0, and I'm seeing a lot of errors in the application log, I think owing to the email router. The error text is "Query execution time of 30.0 seconds exceeded the threshold of 10 seconds".

Here's the query it's executing:

WITH Candidates
        (
            ActivityId
        ) AS
        (SELECT  ActivityId
        FROM     EmailHashBase WITH (NOLOCK)
        WHERE    ActivityId IN
                (SELECT  ActivityId
                FROM     EmailHashBase WITH (NOLOCK)
                WHERE    HashType = 0
                    AND Hash IN (111682,1892164739,45,1824023892,54,3805,125879)
                GROUP BY ActivityId
                HAVING   COUNT(ActivityId) >= 7
                )
            AND HashType = 1
            AND Hash IN (969105075,1418975348,547970098,1044570065,-1578559672,1137188287,-1492206818,1365121987,1893861533,-1313312639,-1829169632,-1685403462,-518982188,1123523219,284291011,-981044541,1790111815,-808308608,-599769785,971845046)
        GROUP BY ActivityId
        HAVING   COUNT(ActivityId) >= 2
        )
SELECT   TOP 1 a.ActivityId
FROM     ActivityPointerBase AS a WITH (NOLOCK)
WHERE    a.ActivityId IN
            (SELECT ActivityId
            FROM    Candidates AS c
            WHERE(
                    (SELECT COUNT(*)
                            FROM    EmailHashBase AS h
                            WHERE   h.ActivityId = c.ActivityId
                                AND h.HashType   = 0
                    )
                    <= 7
                ) 
            )
ORDER BY a.ModifiedOn DESC

Running this query directly against the database takes up to a minute. I've run it using "Set Statistics IO ON" and have following results:

Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'EmailHashBase'. Scan count 17696074, logical reads 53155625, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'ActivityPointerBase'. Scan count 1, logical reads 5060, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

SQL Server Execution Times:
CPU time = 36567 ms,  elapsed time = 36562 ms.

Obviously there's a problem with EmailHashBase. I've added a non-clustered index on the Hash column and rebuilt the indexes, but I'm still getting a high scan and logical read count.

I cannot change the query.

Any suggestions on what I can do to the table to fix this?

Answer 1

Turns out an index had been created by the database tuning adviser that caused the delay. Deleting the index has resolved the issue.