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Posted to issues@impala.apache.org by "Michael Ho (JIRA)" <ji...@apache.org> on 2017/05/24 01:32:04 UTC
[jira] [Created] (IMPALA-5356) Move Expr's fragment local states
from ExprContext to Expr
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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