Daniel Dai created PIG-4128:
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Summary: New logical optimizer rule: ConstantCalculator
Key: PIG-4128
URL: https://issues.apache.org/jira/browse/PIG-4128
Project: Pig
Issue Type: New Feature
Components: impl
Reporter: Daniel Dai
Assignee: Daniel Dai
Fix For: 0.14.0
Attachments: PIG-4128-1.patch
Pig used to have a LogicExpressionSimplifier to simplify expression which also
calculates constant expression. The optimizer rule is buggy and we disable it
by default in PIG-2316.
However, we do need this feature especially in partition/predicate push down,
since both does not deal with complex constant expression, we'd like to replace
the expression with constant before the actual push down. Yes, user may
manually do the calculation and rewrite the query, but even rewrite is
sometimes not possible. Consider the case user want to push a datetime
predicate, user have to write a ToDate udf since Pig does not have datetime
constant.
In this Jira, I provide a new rule: ConstantCalculator, which is much simpler
and much less error prone, to replace LogicExpressionSimplifier.
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