indexes: seeks and scans, what do the numbers mean?

  • hi folks,

    i have a basic level understanding on the differences between a seek and a scan

    but what does it mean when a newly created index has had 31450 seeks - what makes this number up? i dont think its 31450 unique queries etc that have used the index, so is it the total rows returned from queries to date?

    Or is it something completely different 🙂

    thanks

     

    mal

  • It is a seek operation. A query could potentially seek multiple times for different reasons, like the complexity, row lookups, etc.

     

  • so the 31450  figure (now 213677) is possibly the total rows of data returned via the index?

  • No, it's not a row total, as Steve noted.  It's the number of seek operations since the stats for that index were created.

    One query that reads, say 5,000 rows, might use 5000 different seeks to do that, if SQL chose to do the lookups that way.  But it's still not directly a row count, as the access could be a "seek and scan", which does one seek but then reads multiple rows.

    SQL DBA,SQL Server MVP(07, 08, 09) "Money can't buy you happiness." Maybe so, but it can make your unhappiness a LOT more comfortable!

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