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https://issues.apache.org/jira/browse/IOTDB-476?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jialin Qiao closed IOTDB-476.
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> Improve the ExpressionOptimizer
> -------------------------------
>
> Key: IOTDB-476
> URL: https://issues.apache.org/jira/browse/IOTDB-476
> Project: Apache IoTDB
> Issue Type: Improvement
> Components: Core/TsFile
> Reporter: Jialin Qiao
> Assignee: Yuyuan KANG
> Priority: Minor
> Labels: pull-request-available
> Time Spent: 20m
> Remaining Estimate: 0h
>
> Suppose there are two time series: s1, s2 and a sql has a predicate : s1>10
> or time < 10
>
> In the ExpressionOptimizer, the time < 10 will be unfolded with all series,
> then combined with s1>10. Finally, the predicate will be transformed into a
> tree structure:
> ORExpression (
> SingleSeriesExpression(s1, value>10)
> ORExpression(
> SingleSeriesExpression(s1, time>10),
> SingleSeriesExpression(s2, time>10)
> )
> )
> We will construct a SeriesReader for each SingleSeriesExpression in the
> ITimeGenerator.
> This expression could be optimized into the following:
> ORExpression (
> SingleSeriesExpression(s1, value>10 or time>10)
> SingleSeriesExpression(s2, time>10)
> )
>
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