Re: Statistical Analysis

At 20:18 24/07/00 -0400, you wrote:
>Sigh, forgot to mention the solution. There's an undocumented function:
>
> * bool oidrand (oid o, int4 X)-
> * takes in an oid and a int4 X, and will return 'true'
> * about 1/X of the time.
>
>typically used like this:
>
>-- select roughly 1/10 of the tuples
>SELECT * FROM onek WHERE oidrand(onek.oid, 10);
>

It doesnt seem to work as you explain.
For a value of 1 you expect (nearly) all the tuples and two should return
half, but that not what I'm finding.

galore=> select count(*) from topten where room='HI';
count
-----
14
(1 row)

galore=> SELECT * FROM topten WHERE room='HE' and oidrand(topten.oid, 1);
type|data |norder|room |grp
----+-------------------------+------+------+---
B |0764552503 | 1|HE |
B |0751327190 | 1|HE |
B |0718144392 | |HE |
B |0500280754 | |HE |
B |0028610091 | 1|HE |
(5 rows)
galore=> SELECT * FROM topten WHERE room='HE' and oidrand(topten.oid, 2);
type|data |norder|room |grp
----+-------------------------+------+------+---
B |0764552503 | 1|HE |
B |0751327190 | 1|HE |
B |0718144392 | |HE |
(3 rows)
galore=> SELECT * FROM topten WHERE room='HE' and oidrand(topten.oid, 7);
type|data |norder|room |grp
----+-------------------------+------+------+---
B |0751327190 | 1|HE |
B |0718144392 | |HE |
(2 rows)
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