• Was the Tempdb log previously capped?

    No, it wasn't, but it is now (10 GB).

    @ChrisM@Work

    Number of recs returned by your SELECT version of the query is unknown but large...it has now been running for 28 minutes, no 34 minutes; and is still going!!

    What does SELECT PatientKey = P.PatientKey, AgeKey = PM.AgeKey ... mean - in a SELECT query that is? are the assignments just ignored?

    Hmm, just looked at the PatienMonths table - it has 47303750 records and occupies 2,469.805 MB data space and 816.430 MB index space!

    MarkD