From my understanding of external tables they are great if we need multiple 
schemas associated with the same base data. A place where this could come handy 
is if we using custom SerDe implementation. The drawback that I have noticed 
has to do with binary file formats. One will have to use a custom map reduce 
job to generate the base data if you plan to use that as an external table. 
Please feel free to correct me here if I am wrong.


Thanks,
Ranjith

________________________________
From: Shantian Purkad <[email protected]>
To: [email protected] <[email protected]>
Sent: Tue Apr 26 11:18:46 2011
Subject: External tables pros & cons

Hi,

What is the difference between external table and managed tables (apart from 
data being stored outside hive warehouse and not deleted when table is dropped)

Are there any drawbacks of external tables? Or lack of support for certain 
features (such as indexes, joins, subqueries etc etc )?

When and why should one not use external tables?

Thanks and Regards,
Shantian

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