Database Reference
In-Depth Information
Generating test data
DBAs frequently need to generate test data for a variety of reasons, whether it's to set up
a test database or just to generate a test case for an SQL performance issue.
How to do it...
To create a table of test data we need the following:
F
Some rows
F
Some columns
F
Some order
Rows
To generate a lot of rows of data, we use something named a "set returning function".
You can write your own, though PostgreSQL includes a couple of very useful ones.
You can generate a sequence of rows using a query, like the following:
postgres=# SELECT * FROM generate_series(1,5);
generate_series
-----------------
1
2
3
4
5
(5 rows)
or you can generate a list of dates, like the following:
postgres=# SELECT date(generate_series(now(), now() + '1 week', '1
day'));
date
------------
2010-03-30
2010-03-31
2010-04-01
2010-04-02
2010-04-03
2010-04-04
2010-04-05
2010-04-06
(8 rows)
