can you reduce the UDF just to return 1; ?
that should give you a clue what is going on. Random
values usualy point to two suspects
1. mixing 32bit and 64bit
2. using void instead of int
Am 04.11.2012 23:23, schrieb Stefan Kuhn:
> Hi all,
> I have a weired (for me at least) problem with a user defined function,
> written in C. The function seems to return different results in different
> runs (the code of the function does not contain random elements). Basically,
> the function calculates a score based on a column in a table and an input
> value. So I do something like this:
> select * from table order by udf(column, 'input_value') desc;
> For my understanding, this should give the same result always. But if I run
> many statements (execution is from a java program and I can do it in parallel
> threads) so that they overlap (the udf on a large table takes 5-10 s on a
> slow machine), the results of some queries are different. If I have enough
> time between statements, it seems to work, i. e. the result is always the
> same. I would have thought the statements are independent, even if executed
> on different jdbc connections in parallel.
> Does somebody have an idea?
> Or could somebody give an idea on debugging? Normally I would try to debug the
> code to see what goes on, but how can I do this in a udf? Can I log in the
> Thanks for any hints,