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From "godfrey he (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-5406) add normalization phase for predicate logical plan rewriting between decorrelate query phase and volcano optimization phase
Date Wed, 04 Jan 2017 07:21:58 GMT
godfrey he created FLINK-5406:
---------------------------------

             Summary: add normalization phase for predicate logical plan rewriting between
decorrelate query phase and volcano optimization phase
                 Key: FLINK-5406
                 URL: https://issues.apache.org/jira/browse/FLINK-5406
             Project: Flink
          Issue Type: New Feature
          Components: Table API & SQL
            Reporter: godfrey he


Normalization phase is for predicate logical plan rewriting and is independent of cost module.
The rules in normalization phase do not need to repeatedly applied to different logical plan
which is different to volcano optimization phase. And the benefit of normalization phase is
to reduce the running time of volcano planner.

`ReduceExpressionsRule` can apply various simplifying transformations on RexNode trees. Currently,
there are two transformations:
1) Constant reduction, which evaluates constant subtrees, replacing them with a corresponding
RexLiteral
2) Removal of redundant casts, which occurs when the argument into the cast is the same as
the type of the resulting cast expression

the above transformations do not depend on the cost module,  so we can move the rules in `ReduceExpressionsRule`
from DATASET_OPT_RULES/DATASTREAM_OPT_RULES to DataSet/DataStream Normalization Rules.



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