Logical Optimizer: change outer join into regular join
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Key: PIG-1322
URL: https://issues.apache.org/jira/browse/PIG-1322
Project: Pig
Issue Type: New Feature
Components: impl
Affects Versions: 0.7.0
Reporter: Daniel Dai
Assignee: Daniel Dai
In some cases, we can change the outer join into a regular join. The benefit is
regular join is easier to optimize in subsequent optimization.
Example:
C = join A by a0 LEFT OUTER, B by b0;
D = filter C by b0 > 0;
=>
C = join A by a0, B by b0;
D = filter C by b0 > 0;
Because we made this change, so PushUpFilter rule can further push the filter
in front of regular join which otherwise cannot.
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