SAMPLE Clause

The SAMPLE clause allows you to run the query on a sample from the base table. This can significantly speed up processing of queries, at the expense of accuracy in the result. Samples can also be used to quickly see a snapshot of the data when exploring a data set. The sample clause is applied right after anything in the FROM clause (i.e. after any joins, but before the where clause or any aggregates). See the sample page for more information.

Examples

-- select a sample of 1% of the addresses table using default (system) sampling
SELECT *
FROM addresses
USING SAMPLE 1%;
-- select a sample of 1% of the addresses table using bernoulli sampling
SELECT *
FROM addresses
USING SAMPLE 1% (BERNOULLI);
-- select a sample of 10 rows from the subquery
SELECT *
FROM (SELECT * FROM addresses)
USING SAMPLE 10 ROWS;

Syntax