A couple of questions present. You mention that selecting from the whole table takes 5-10s so I assume you have a lot of records. is the data not in flux? are you sure? these conflict queries are all on the same server?
i would have structured the query like so: select *, udf(column,'value') AS u from table order by u; I suspect it might reduce the number of udf invocations.. the order by clause is frequently referred to in the process of sorting.. keeping that static instead of dynamic might sanitize your issue. On 2012-11-04 4:24 PM, "Stefan Kuhn" <stef...@web.de> wrote: 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 -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/mysql
