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Posted to dev@iotdb.apache.org by "Jialin Qiao (Jira)" <ji...@apache.org> on 2020/02/27 05:47:00 UTC

[jira] [Closed] (IOTDB-476) Improve the ExpressionOptimizer

     [ https://issues.apache.org/jira/browse/IOTDB-476?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jialin Qiao closed IOTDB-476.
-----------------------------

> 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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