You can also take a look at the beta of the _Programming Pig_ book, http://ofps.oreilly.com/titles/9781449302641/
Specialized joins are described in chapter six. How to do semi-
joins is also described under Cogroup in the same chapter. Any
feedback you have on the descriptions would be welcomed.
Alan.
On Apr 12, 2011, at 9:55 PM, Dmitriy Ryaboy wrote:
Renato, slides 20-23 on this presentation describe the
implementations of
the joins:
http://squarecog.wordpress.com/2009/11/03/apache-pig-apittsburgh-hadoop-user-group/
You can also search the pig wiki for design docs for each join.
D
On Tue, Apr 12, 2011 at 9:48 PM, Renato Marroquín Mogrovejo <
[email protected]> wrote:
Hi there,
I have some questions about how PIG performs joins. The site says
there are
three types of specialized joins: Replicated, skew, and merge
joins. I
wanted to know these implementations. For instance, what about the
regular
type of join? Is there a difference between the repartition join
(org.apache.hadoop.contrib.utils.join) and the regular join
implemented in
PIG? Is the merge join what is called a map-side join (where input is
sorted
and just regular scans are done)?
And about PIG join framework[1], are there other specific
implementation
done? e.g. Semi-joins?
Thanks in advance.
Renato M.
