Select a random sample of results from a query result

Question

This question asks about getting a random(ish) sample of records on SQL Server and the answer was to use TABLESAMPLE. Is there an equivalent in Oracle 10?

Answer 1

This in not a perfect answer but will get much better performance.

SELECT  *
FROM    (
    SELECT  *
    FROM    mytable sample (0.01)
    ORDER BY
            dbms_random.value
    )
WHERE rownum <= 1000

Sample will give you a percent of your actual table, if you really wanted a 1000 rows you would need to adjust that number. More often I just need an arbitrary number of rows anyway so I don't limit my results. On my database with 2 million rows I get 2 seconds vs 60 seconds.

select * from mytable sample (0.01)