TABLESAMPLE returns wrong number of rows?

Question

I\'ve just discovered the TABLESAMPLE clause but surprisingly it doesn\'t return the number of rows i\'ve specified.

The table that i\'ve used has ~14M rows and i wa

Answer 1

I've observed the same.

The page explanation definitely makes sense and rings a bell - You should see much more predictable row counts when your row size is fixed. Try it on a table with no nullable or variable-length columns.

In fact I just used it to prove a theory about using it to update (you were probably spurred by the same question I was), and choosing TABLESAMPLE (50000 ROWS) actually affected 49,849 rows.