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Hive, mail # user - Map side join


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Abhishek 2012-06-13, 15:13
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Tucker, Matt 2012-06-13, 15:20
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Re: Map side join
Aniket Mokashi 2012-06-18, 08:08
Hive also have something called uniquejoin. May be you are looking for
that. I cannot find documentation for your reference but you can do a jira
search.
It allows you to perform joining multiple sources with same key, mapside.
(all sources should have the same key)

~Aniket

On Wed, Jun 13, 2012 at 8:20 AM, Tucker, Matt <[EMAIL PROTECTED]>wrote:

> Hi,
>
> Assuming that 4 tables are small enough to fit in the Distributed Cache,
> the joins between the tables all need to join against a common key.
>
> Example:
> set hive.auto.convert.join=true;
> SELECT *
> FROM large
>    JOIN smalla ON
>        large.key = smalla.key1
>    JOIN smallb ON
>        large.key = smallb.key2
>    JOIN smallc ON
>        large.key = smallc.key3
>    JOIN smalld ON
>        large.key = smalld.key4;
>
> Having a different join key will push the join off into a different task,
> as will the order of the join condition. In this example, large.key was
> always on the left side of the join conditions.
>
>
> Matt Tucker
>
> -----Original Message-----
> From: Abhishek [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, June 13, 2012 11:13 AM
> To: [EMAIL PROTECTED]
> Subject: Map side join
>
> Hi all,
>
> How map side join in hive, can be used to join multiple tables(suppose 5
> tables).
>
> Regards
> Abhishek
>
> Sent from my iPhone
>

--
"...:::Aniket:::... Quetzalco@tl"
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Souvik Banerjee 2012-12-07, 19:58