SQL Server Performance Forum – Threads Archive
Incorrect Query PlanHi, I’ve got a table with 50 milion rows. It has a composite non-clustered index on a smalldatetime field and a smallint field. When I SELECT from the table specifying a date in the WHERE clause, it does a table scan rather than using the index. If I supply a hint to force it to use the index the query is much quicker. There are no other indexes on the table. The indexes are rebuilt daily (DBREINDEX). The SELECT with the hint takes 8 secs, without takes 50 secs. Does not anyone know why a table scan is being used.
The table does not have cluster index? Luis Martin
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Changed index to clustered – query plan now uses this in the SELECT – takes 8 secs. Doesn’t explain why the index was not used when it was non-clustered and instead did a table scan.