Re: select random order by random

Chris Browne wrote:
> If I replicate your query, with extra columns, AND NAMES, I get the following:
>
> test(at)[local]:5433=# select random() as r1, random() as r2, random() as r3 from generate_series(1,10) order by random();
> r1 | r2 | r3
> --------------------+--------------------+-------------------
> 0.0288224648684263 | 0.904462072532624 | 0.27792159980163
> 0.144174488261342 | 0.406729203648865 | 0.452183415647596
> ...
> It is indeed somewhat curious that the query parser chose to interpret
> that the "order by random()" was referring to column #1.

And even more curiously, IMHO, even specifying
column names isn't enough. Note that this:

li=# select * from (select (random()*10)::int as a, (random()*10)::int as b from generate_series(1,10) order by a) as x order by b;
a | b
---+----
0 | 8
1 | 10
3 | 4
4 | 8
5 | 1
5 | 9
6 | 4
6 | 5
8 | 4
9 | 0
(10 rows)

is sorted by "a" even though the outermost "order by"
clause explicitly said to order by "b".

Seems like it's a known odd behavior ...
http://archives.postgresql.org/pgsql-general/2006-11/msg01523.php
http://archives.postgresql.org/pgsql-general/2006-11/msg01539.php
http://archives.postgresql.org/pgsql-general/2006-11/msg01544.php