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07-06-2015
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07-07-2015
07:37 AM
Hi Alex, Thanks for your fast response. I have couple of questions more 😛 1) I see that the KnuthVariance returns Double, but when I try it in my code having Finalize function return a Double I get, Analysis Exception: Could not find function func_nameUpdate(double,double,double) returns double in 'HDFS_so_filepath' Check that function name, agruments and return types are correct. I am curious how the in-built functions have that feature. Pls do let me know if I am missing something. 2) If cloudera needs to fix it, pls let me know on which CDH and impala version, fix might be released. Thanks !!!
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07-06-2015
02:23 PM
Hi, I have been working on creating custom User Defined Aggregate Functions (UDAF), looking at the example provided here. Here Variance and standard deviation is calculated on a Impala column. Since we have quite a lot varibles to calculate like sum, sum of squares and count, we use a C++ struct and serialize it as a string, so that data is passed to init, update, merge and finalize phases. My questions: 1) Can we have a Double return type instead of String. 2) Where can we find the implementations of Impala buitl-in functions like min(), sum(), max() since these functions return double. Any suggestions are welcome. Thanks !!!
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