working on issue "Improve the ExpressionOptimizer"

[Yuyuan KANG <ky...@mails.tsinghua.edu.cn>]

Hi, all


I'm working on issue [IOTDB-476], "Improve the ExpressionOptimizer".


-------------------
Yuyuan KANG
School of Software, Tsinghua University

Re: working on issue "Improve the ExpressionOptimizer"

[Yuyuan KANG <ky...@mails.tsinghua.edu.cn>]

Hi, all

ExpressionOptimizer is improved to generate more efficient expressions. For example, before the modification, the query s1 > 10 or time < 1 will be tranformed to

ORExpression (
   SingleSeriesExpression(s1 , value >10)
   ORExpression(
       SingleSeriesExpression(s1 , time <10),
       SingleSeriesExpression(s2 , time <10)
    )
)

With the new logic, the query will be transformed to

ORExpression (
   SingleSeriesExpression(s1 , value >10 or time <10)
   SingleSeriesExpression(s2 , time <10)
)

With less SingleSeriesExpressions, the query can be executed more efficiently.

Experiments shows that, if we have 3 devices, each containing 3 sensors, and the query is t<4838 or d2.s2>0.5, the latency decreases around 10%.

-------------------
Yuyuan KANG
School of Software, Tsinghua University

在2020-02-14 09:53:42，Yuyuan KANGkyy19@mails.tsinghua.edu.cn写道：

Hi, all


I'm working on issue [IOTDB-476], "Improve the ExpressionOptimizer".


-------------------
Yuyuan KANG
School of Software, Tsinghua University