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https://issues.apache.org/jira/browse/PIG-28?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Olga Natkovich resolved PIG-28.
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Resolution: Fixed
closing since this is being addressed by pipeline rewrite
> Independence of Logical Plan from Physical Plan
> -----------------------------------------------
>
> Key: PIG-28
> URL: https://issues.apache.org/jira/browse/PIG-28
> Project: Pig
> Issue Type: Bug
> Components: impl
> Reporter: Antonio Magnaghi
>
> The implementation of a Pig Logical Plan is currently closely tied with
> implementation details of the Physical Plan.
> For instance, the construction of the tree of Logical Operators puts in place
> the data pipes in conjunction with the construction of Eval Spec and Cond
> nodes. Data pipes are utilized later on during the execution of the query.
> Conceptually, this appears to obfuscate the code.
> It would be nice to remove or reduce this tight coupling. This aspect may
> also be relevant to the proposal to provide an abstraction layer for Pig,
> where front-end activities are clearly separated from back-end tasks and
> responsibilities (see wiki at:
> http://wiki.apache.org/pig/PigAbstractionLayer)
> Two possible alternatives initially discussed could be:
> 1.) to decouple logical from physical part of plan construction by having two
> distinct sets of Eval Specs: a Logical Eval Spec/Cond set without physical
> plan details and a Physical Eval Spec/Cond set that addresses the aspects of
> the physical plan.
> 2.) to merge the logical operators with the local physical operators (used by
> the LocalPlanCompiler) and preserve the MapReduce physical operator.
> The second option may be preferable because less extensive changes are
> involved. Additionally, choosing the second option would integrate the Local
> Plan data structures into the core code packages: long term this could
> simplify the maintenance and support of the Local Plan construction.
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