0

The SQL Server documentation for sp_updatestats states that:

If 'resample' is not specified, sp_updatestats updates statistics by using the default sampling.

How exactly does SQL Server calculate the default sample size?

Improve this question

1 Answer 1

Reset to default
1

That's a good question. If you're interested in statistics, you might want to give Elisabeth Redei's excellent blog post a read:

Lies, Damned Lies and Statistics

It explains that, as the table size increases, the default sampling rate becomes insufficient to accurately represent the table's contents. It also provides a formula that she states is used in calculating the default sample set size (Rowmodctr 500 + 20% of total rows).

Improve this answer
1
  • that's wrong, is the formula to determine if a statistics is out dated and then fires un update. the default sample size must be calculated with some other formula that I'm searching too.
    – user208693
    Commented Feb 9, 2014 at 12:05

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .