The Costs Of Statistics Updates With FULLSCAN

Kendra Little explains what happens when you update a table’s statistics with FULLSCAN:

On my test instance, the command that uses the default sampling takes 6 seconds to complete.

The command which adds “WITH FULLSCAN” takes just over five minutes to complete.

The reason is that those two little words can add a whole lot of extra IO to the work of updating statistics.

Kendra shows the query plans for each statistics update in some detail.  It’s a very interesting post, well worth taking the time to read.

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