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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (PIG-4128) New logical optimizer rule: ConstantCalculator
Date Tue, 26 Aug 2014 22:37:57 GMT

     [ https://issues.apache.org/jira/browse/PIG-4128?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Daniel Dai updated PIG-4128:
----------------------------

    Attachment: PIG-4128-3.patch

Addressing Thejas' review comments.

> 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-4128-2.patch, PIG-4128-3.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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