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Hive >> mail # user >> Starting with Hive - writing custom SerDe


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Fernando Andrés Doglio Tu... 2012-11-29, 13:38
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RE: Starting with Hive - writing custom SerDe
You might save yourself a lot of work by pre-processing the data, before putting it into Hive. A Python script should be able to find all the fields, and change the data to plan tab-separated text. This will load directly into Hive, and removes the need to write a custom SerDe.

Chuck Connell
Nuance R&D Data Team
Burlington, MA

From: Fernando Andrés Doglio Turissini [mailto:[EMAIL PROTECTED]]
Sent: Thursday, November 29, 2012 8:39 AM
To: [EMAIL PROTECTED]
Subject: Starting with Hive - writing custom SerDe

Hello everyone, I'm starting to play around with Hive, and I have to load a traffic data log file into a table. My problem is that the lines of the file don't really have a nice separator for each field (on the same line, there are serveral blank or hyphens or single blank spaces used as separators)...
So after looking around for a while, I found that I have to write a custom SerDe in order to tell Hive how to parse those lines.

I've also found that I can only write them using Java (unlike UDFs for pig for instance, which can be written using other languages), is this correct?
Furthermore, I wanted to know if anyone can point me into the direction of some sort of documentation  that describes the process of writing a SerDe. I've found examples around the internet, but none of them explain what exactly is each method supposed to do (I'm talking about the methods supplied by the SerDe interface).

Thanks in advance!

Best!
Fernando
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Connell, Chuck 2012-11-29, 14:53
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Dean Wampler 2012-11-29, 15:09