Set random value from set I need to put some random values into database, but I don't want to end up with completely randomized text (like 7hfg43d3). Instead I would like to randomly pick one of values supplied by myself.
Nice idea. I suggest two minor simplifications:

('{Foo,Bar,Poo}'::text[])[ceil(random()*3)]



Simpler syntax using an array literal ('{Foo,Bar,Poo}'::text[])
Shortens the string for longer lists.
Additional benefit: explicit type declaration works for any type, not just for text. Your original idea happens to output text, because that's the default type for string literals.
Use ceil() instead of floor() + 1. Same result.


OK, theoretically, the lower border could be 0 precisely, as hinted in your comment, since random() produces (quoting the manual here):


  random value in the range 0.0 &lt;= x &lt; 1.0


However, I have never seen that happen. Run a couple of million tests:

SELECT count(*)
FROM   generate_series(1,1000000)
WHERE  ceil(random())::int = 0;


-> SQLfiddle

To be perfectly safe, though, you can use Postgres custom array subscripts and still avoid the extra addition:

('[0:2]={Foo,Bar,Poo}'::text[])[floor(random()*3)]


Details under this related question on SO.

Or better yet, use trunc(), that's a bit faster.

('[0:2]={Foo,Bar,Poo}'::text[])[trunc(random()*3)]