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From:walter harms Date:November 5 2012 6:45pm
Subject:Re: UDF behaves non-deterministic
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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 
> udf?
> Thanks for any hints,
> Stefan
UDF behaves non-deterministicStefan Kuhn4 Nov
  • Re: UDF behaves non-deterministicDan Nelson5 Nov
  • Re: UDF behaves non-deterministicwalter harms5 Nov
  • Re: UDF behaves non-deterministichsv5 Nov
    • Re: UDF behaves non-deterministicStefan Kuhn5 Nov
Re: UDF behaves non-deterministicMichael Dykman4 Nov
  • Re: UDF behaves non-deterministicStefan Kuhn4 Nov