What is Range Scan in SQL Server?

  • I'm trying to find out what a Range Scan is and how to judge this value in Performance Monitor. When googling the Net I find a lot of hits on Oracle, not so much for SQL Server, nothing sofar in relation with Performance Monitor. No explaination in BOL found.

    Can any1 point me to some explaination, or tell me here how to interpret this counter in PerfMon?

    Greetz,
    Hans Brouwer

  • It's simply scanning an index along the logical chain of the index instead of along the storage chain, an allocation scan. This is usually from an ORDER BY, but can be a part of the normal look-ups for an index if the data needs to be logically ordered to satisfy the search. Lookup key range locking in BOL for some more details.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

  • Tnx for the heads-up, Grant. I still am not sure if this counter is significant in PerfMon; I think not.

    Greetz,
    Hans Brouwer

  • In my opinion, this would not be a primary counter for checking performance. I'd use it once I've already identified range scans as an issue because of excessive waits or high i/o or high cpu, stuff like that.

    "The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood"
    - Theodore Roosevelt

    Author of:
    SQL Server Execution Plans
    SQL Server Query Performance Tuning

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