# Set A Seed For The Random Number Generator

In PostgreSQL, the internal seed for the random number generator is a
run-time configuration parameter. This `seed` parameter can be set to a
particular seed in order to get some determinism from functions that utilize
the random number generator. The seed needs to be something between `0` and
`1`.

We can see this in action by setting the seed and then invoking `random()` a
couple times. Doing this twice, we will see the reproducibility we can
achieve with a seed.

```sql
> set seed to 0.1234;
SET

> select random();
      random
-------------------
 0.397731185890734

> select random();
      random
------------------
 0.39575699577108
(1 row)

> set seed to 0.1234;
SET

> select random();
      random
-------------------
 0.397731185890734

> select random();
      random
------------------
 0.39575699577108
```

The seed can also be configured with the `setseed()` function.

See [the PostgreSQL
docs](http://www.postgresql.org/docs/8.3/static/sql-set.html) for more
details.