See initial sections in
http://infolab.stanford.edu/~olston/publications/vldb09.pdf for overview
of logical plan.
LogicalPlanGenerator.g is a the place where logical plan is created from
parse tree. You would need to look at antlr basics to understand that.
(almost?) all pig relational operations correspond to a subclass of
LogicalRelationalOperator in org.apache.pig.newplan.logical.relational
package. Expressions within a relation are subclasses of
LogicalExpressionOperator.
This document talks about motivations behind the logical plan redesign
and about some special operations like LOInnerLoad, and special handling
for foreach operator.
http://wiki.apache.org/pig/PigLogicalPlanOptimizerRewrite
-Thejas
On 1/29/12 8:41 PM, Prasanth J wrote:
Hello Everyone
I am a newbie to pig. I was going through
https://cwiki.apache.org/PIG/guide-for-new-contributors.html, specifically
the grammar files to start off with.
I could not understand how LogicalPlanGenerator.g works by looking into the
grammar file. Also there isn't much documentation available which explains
how logical plans are generated for different pig operators. Is there any
reference from which I can learn more about the internals (especially the
logical plan generation part)?
Thanks
Prasanth
