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From "Mich Talebzadeh" <>
Subject RE: ORC format
Date Mon, 01 Feb 2016 15:49:13 GMT
Use orcfiledump to see the stats for each column etc




hive --orcfiledump --rowindex 1,2 /user/hive/warehouse/oraclehadoop.db/orctest/000000_0



Dr Mich Talebzadeh




Sybase ASE 15 Gold Medal Award 2008

A Winning Strategy: Running the most Critical Financial Data on ASE 15

Author of the books "A Practitioner’s Guide to Upgrading to Sybase ASE 15", ISBN 978-0-9563693-0-7.

co-author "Sybase Transact SQL Guidelines Best Practices", ISBN 978-0-9759693-0-4

Publications due shortly:

Complex Event Processing in Heterogeneous Environments, ISBN: 978-0-9563693-3-8

Oracle and Sybase, Concepts and Contrasts, ISBN: 978-0-9563693-1-4, volume one out shortly <> 


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From: Philip Lee [] 
Sent: 01 February 2016 15:27
Subject: Re: ORC format



when making ORC from CSV, 

for indexing every key on each coulmn is made, or a primary on a table is made ?


If keys are made on each column in a table, accessing any column in some functions like filtering
should be faster.


On Mon, Feb 1, 2016 at 4:21 PM, Philip Lee < <>
> wrote:



I experiment the performance of some systems between ORC and CSV file.

I read about ORC documentation on Hive website, but still curious of some things.


I know ORC format is faster on filtering or reading because it has indexing.

Has it advantage of joining two tables of ORC dataset as well?


Could you explain about it in detail?

When experimenting, it seems like it has some advantages of joining in some aspect, but not
quite sure what characteristic of ORC make this happening rather than CSV.








Hae Joon Lee


Now, in Germany,

M.S. Candidate, Interested in Distributed System, Iterative Processing

Dept. of Computer Science, Informatik in German, TUB

Technical University of Berlin


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M.S. Candidate, Computer Architecture Laboratory

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