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
This document talks about motivations behind the logical plan redesign
and about some special operations like LOInnerLoad, and special handling
for foreach operator.
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)?