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PostgreSQL 9 Administration Cookbook - Second Edition by Simon Riggs, Gianni Ciolli, Hannu Krosing, Gabriele Bartolini

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Generating test data

DBAs frequently need to generate test data for a variety of reasons, whether it's for setting up a test database or just for generating a test case for a SQL performance issue.

How to do it…

To create a table of test data, we need the following:

  • Some rows
  • Some columns
  • Some order

The steps are as follows:

  1. First, 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)
    

    Alternatively, you can generate a list of dates, like this:

    postgres=# SELECT date(generate_series(now(), ...

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