Jinfeng Ni created DRILL-3754:
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Summary: Remove redundancy in run-time generated code for common
column references.
Key: DRILL-3754
URL: https://issues.apache.org/jira/browse/DRILL-3754
Project: Apache Drill
Issue Type: Bug
Components: Execution - Codegen
Affects Versions: 1.1.0
Reporter: Jinfeng Ni
Assignee: Jinfeng Ni
Fix For: 1.2.0
When a operator (Filter, project) has expression which refer one same field
multiple times, Drill will initialize a value vector and do value holder
assignment for each field reference in the run-time generated code. The
redundancy might impact the expression evaluation, after the compiled code is
executed over large number of incoming rows.
This has been seen in recent performance issue reported on the drill user list,
where the query contains multiple multiple in list filter conditions.
In this JIRA, we'll remove the redundancy for the common field reference, so
that only one initialization and assignment happen in the run-time generated
code.
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