Table Sampling

Kevin Feasel

2015-12-17

T-SQL

Ginger Grant shows a couple of techniques for sampling from tables:

The random sample that TABLESAMPLE provides is based on the number of data pages, not the number of records. If you want the number of rows to be specifically limited you will need to use Top(n) as well. I’ve written all my samples based upon AdventureWorksDW so you can run them for yourself later. I’ve listed the variety of ways to call TABLESAMPLE and shown the number of records returned.

TABLESAMPLE is useful for spelunking, but is somewhat limited otherwise.

Related Posts

Dealing With String Parsing In T-SQL

Andy Mallon has written a T-SQL function to parse file paths from strings: Writing & reading code is easier if you understand the logic before attacking the code. I find this to be particularly important when you anticipate complicated code. SQL Server sucks at parsing strings, so I anticipate complicated code. How do you identify […]

Read More

The Joy Of OUTPUT

Mark Wilkinson shows off some fun stuff you can do with the OUTPUT clause: A common command in the Linux world is the tee command. What tee allows you to do is pipe the output of a command to a file as well as the console. This same functionality can be implemented using multiple OUTPUT clauses in a T-SQL statement. In […]

Read More

Categories

December 2015
MTWTFSS
« Nov Jan »
 123456
78910111213
14151617181920
21222324252627
28293031