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[optimizer][CBO] count(*) with table statistics #914

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BohuTANG opened this issue Jun 26, 2021 · 1 comment · Fixed by #960
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[optimizer][CBO] count(*) with table statistics #914

BohuTANG opened this issue Jun 26, 2021 · 1 comment · Fixed by #960
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@TennyZhuang
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C-feature Category: feature community-take

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@BohuTANG
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BohuTANG commented Jun 26, 2021 •
edited by sundy-li
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Summary

For query select count(*) from system.numbers(100000), ReadDataSourcePlan has Statistics:
https://github.com/datafuselabs/datafuse/blob/28c8e3eda9fb8de881635343d3225b3e7be07b4b/common/planners/src/plan_read_datasource.rs#L17-L26

In this case, we can use the read_rows as the final count:
https://github.com/datafuselabs/datafuse/blob/28c8e3eda9fb8de881635343d3225b3e7be07b4b/common/planners/src/plan_statistics.rs#L6-L11

We need a StatisticsConstant optimizer rule, like:
https://github.com/apache/arrow-datafusion/pull/620/files
@BohuTANG BohuTANG added the C-feature Category: feature label Jun 26, 2021
@BohuTANG BohuTANG added this to the v0.5 milestone Jun 26, 2021
@BohuTANG BohuTANG mentioned this issue Jun 26, 2021
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/assignme

@TennyZhuang TennyZhuang mentioned this issue Jul 1, 2021
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@BohuTANG BohuTANG mentioned this issue Jul 5, 2021
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[optimizer][CBO] count(*) with table statistics TennyZhuang/datafuse
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