Select a random sample of results from a query result

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

The SAMPLE clause will give you a random sample percentage of all rows in a table.

For example, here we obtain 25% of the rows:

SELECT * FROM emp SAMPLE(25)

The following SQL (using one of the analytical functions) will give you a random sample of a specific number of each occurrence of a particular value (similar to a GROUP BY) in a table.

Here we sample 10 of each:

SELECT * FROM (
SELECT job, sal, ROW_NUMBER()
OVER (
PARTITION BY job ORDER BY job
) SampleCount FROM emp
)
WHERE SampleCount <= 10

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)