Exactly, rand() UDF in ib_udf is completely broken.
The seed is set each time it is called !!
and is set from time() function which has 1 second precision.
So, the current function of rand() is that it returns
encrypted time :-/

What programming language do you use ?
It is simple to write your own and working udf.

Ivan

----- Original Message -----
From: "Walter Ogston" <ogstoncw@...>
To: <firebird-support@yahoogroups.com>
Sent: Thursday, June 24, 2004 10:07 PM
Subject: [firebird-support] Rand function in ib_udf


> Fear friends,
>
> I am new at Firebird, udfs and stored procs, and using the rand function
> from ib_udf in a stored procedure defined as follows:
>
> SET TERM ^;
> alter procedure INSERT_KEYS
> (proj integer, number_of_keys integer)
> returns (keys_created integer)
> AS
> declare variable i integer;
> BEGIN
> keys_created = 0;
> i = number_of_keys;
> while (i > 0) do
> begin
> insert into answersheet (PROJECT_NUMBER, ANSWER_NUMBER)
> values (proj, Rand() * (999999999 - 100000000) + 100000000);
> keys_created = keys_created + 1;
> i = i - 1;
> end
> END ^
> SET TERM ; ^
>
> The idea is to create a set of random 9-digit values (cardinality =
> number_of_keys) for answer_number. When I call this function with
> number_of_keys = 1 it works fine, but setting number_of_keys >= 2 I get a
> key violation. Primary key of answersheet relation is (project_number;
> answer_number).
>
> It looks like the udf function Rand is not getting called again but is
> using a cached return value, or else it is being called with the same seed
> (according to the documentation in ib_udf.sql "random number generator is
> seeded using the current time").
>
> Source for rand (from
> http://cvs.sourceforge.net/viewcvs.py/*checkout*/firebird/interbase/extlib/i
> b_udf.c?rev=1.3) is:
>
> double EXPORT IB_UDF_rand() { srand( (unsigned)time (NULL)); return
> ((float) rand() / (float) RAND_MAX); }
>
> Any ideas how to fix or work around this problem?
>
> TIA
>
> Walter
> /*----------------
> C. Walter Ogston
> ogstoncw@... Kalamazoo, Michigan
> */