simulate NTILE(n) , rank() functionality in pig
-----------------------------------------------
Key: PIG-821
URL: https://issues.apache.org/jira/browse/PIG-821
Project: Pig
Issue Type: New Feature
Components: impl
Affects Versions: 0.2.0
Environment: mithril gold -gateway 4000
Reporter: Rekha
Fix For: 0.2.0
Hi,
I came across a job which has some processing which I cant seem to get easily
over-the-counter from pig.
These are NTILE() /rank() operations available in oracle.
While I am trying to write a UDF, that is not working out too well for me yet..
:(
I have a ntile(n) over (partititon by x, y, z order by a desc, b desc)
operation to be done in pig scripts.
Is there a default function in pig scripting which can do this?
For example, lets consider a simple example at
http://download.oracle.com/docs/cd/B14117_01/server.101/b10759/functions091.htm
So here, how would we ideally substitute NTILE() with? any pig counterpart
function/udf?
SELECT last_name, salary, NTILE(4) OVER (ORDER BY salary DESC)
AS quartile FROM employees
WHERE department_id = 100;
LAST_NAME SALARY QUARTILE
------------------------- ---------- ----------
Greenberg 12000 1
Faviet 9000 1
Chen 8200 2
Urman 7800 2
Sciarra 7700 3
Popp 6900 4
In real case, i have ntile over multiple columns, so ideal way to find
histograms/boundary/spitting out the bucket number is needed.
Similarly a pig function is required for rank() over(partition by a,b,c order
by d desc) as e
Please let me know soon.
Thanks & Regards,
/Rekha
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