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From "Michael Ho (JIRA)" <j...@apache.org>
Subject [jira] [Created] (IMPALA-5356) Move Expr's fragment local states from ExprContext to Expr
Date Wed, 24 May 2017 01:32:04 GMT
Michael Ho created IMPALA-5356:
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             Summary: Move Expr's fragment local states from ExprContext to Expr
                 Key: IMPALA-5356
                 URL: https://issues.apache.org/jira/browse/IMPALA-5356
             Project: IMPALA
          Issue Type: Task
          Components: Backend
    Affects Versions: Impala 2.8.0
            Reporter: Michael Ho
            Assignee: Michael Ho
            Priority: Minor


Currently, Exprs' FRAGMENT_LOCAL states are stored in their FunctionContext which is part
of ExprContext. Usually, these states are evaluated during Prepare() phase of ExprContext.

Once https://gerrit.cloudera.org/#/c/5483 is committed, these fragment local states will be
initialized as part of the expression evaluators' initialization.  Ideally, these states should
be initialized once and stashed along with the Expr stored in the fragment states instead
of having one copy of it per fragment instance. Note that some of these FRAGMENT_LOCAL states
are not exactly cheap to initialize (e.g. LIKE predicate may allocate a RE object with the
compiled regexp).



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