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From "John Sichi (JIRA)" <>
Subject [jira] [Commented] (HIVE-1545) Add a bunch of UDFs and UDAFs
Date Thu, 01 Sep 2011 21:38:10 GMT


John Sichi commented on HIVE-1545:

I'm way behind on the PDK (probably not gonna make it for 0.8), but I'm planning to rework
the UDFUtils into annotations as part of it.

Cyril, I think they are mostly used for validation purposes, in which case you can just comment
out the calls for now if you want to use the UDF without validation.

> Add a bunch of UDFs and UDAFs
> -----------------------------
>                 Key: HIVE-1545
>                 URL:
>             Project: Hive
>          Issue Type: New Feature
>          Components: UDF
>            Reporter: Jonathan Chang
>            Assignee: Jonathan Chang
>            Priority: Minor
>         Attachments: core.tar.gz, ext.tar.gz, udfs.tar.gz, udfs.tar.gz
> Here some UD(A)Fs which can be incorporated into the Hive distribution:
> UDFArgMax - Find the 0-indexed index of the largest argument. e.g., ARGMAX(4, 5, 3) returns
> UDFBucket - Find the bucket in which the first argument belongs. e.g., BUCKET(x, b_1,
b_2, b_3, ...), will return the smallest i such that x > b_{i} but <= b_{i+1}. Returns
0 if x is smaller than all the buckets.
> UDFFindInArray - Finds the 1-index of the first element in the array given as the second
argument. Returns 0 if not found. Returns NULL if either argument is NULL. E.g., FIND_IN_ARRAY(5,
array(1,2,5)) will return 3. FIND_IN_ARRAY(5, array(1,2,3)) will return 0.
> UDFGreatCircleDist - Finds the great circle distance (in km) between two lat/long coordinates
(in degrees).
> UDFLDA - Performs LDA inference on a vector given fixed topics.
> UDFNumberRows - Number successive rows starting from 1. Counter resets to 1 whenever
any of its parameters changes.
> UDFPmax - Finds the maximum of a set of columns. e.g., PMAX(4, 5, 3) returns 5.
> UDFRegexpExtractAll - Like REGEXP_EXTRACT except that it returns all matches in an array.
> UDFUnescape - Returns the string unescaped (using C/Java style unescaping).
> UDFWhich - Given a boolean array, return the indices which are TRUE.
> UDFJaccard
> UDAFCollect - Takes all the values associated with a row and converts it into a list.
Make sure to have: set = false;
> UDAFCollectMap - Like collect except that it takes tuples and generates a map.
> UDAFEntropy - Compute the entropy of a column.
> UDAFPearson (BROKEN!!!) - Computes the pearson correlation between two columns.
> UDAFTop - TOP(KEY, VAL) - returns the KEY associated with the largest value of VAL.
> UDAFTopN (BROKEN!!!) - Like TOP except returns a list of the keys associated with the
N (passed as the third parameter) largest values of VAL.
> UDAFHistogram

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