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https://issues.apache.org/jira/browse/CALCITE-4223?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17202725#comment-17202725
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Chunwei Lei commented on CALCITE-4223:
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Let's think about it in another way. A good interface is usually extendable and
easily-and-widely-used by others, right? But what I find is that nobody uses
the way you propose to introduce column statistics, including Flink[1],
Drill[2]. I think it deserves to think twice. I am also glad to hear what
others think about it.
[1]https://github.com/apache/flink/blob/master/flink-table/flink-table-common/src/main/java/org/apache/flink/table/plan/stats/ColumnStats.java
[2]https://github.com/apache/drill/blob/master/metastore/metastore-api/src/main/java/org/apache/drill/metastore/statistics/ColumnStatistics.java
> Introducing column statistics to RelOptTable
> --------------------------------------------
>
> Key: CALCITE-4223
> URL: https://issues.apache.org/jira/browse/CALCITE-4223
> Project: Calcite
> Issue Type: Improvement
> Reporter: Chunwei Lei
> Assignee: Chunwei Lei
> Priority: Major
> Labels: pull-request-available
> Time Spent: 40m
> Remaining Estimate: 0h
>
> Many systems depend on column statistics to compute more accurate stats, such
> as NDV, average column size, and so on. It would be nice if Calcite can
> provide such an interface.
> Column statistics might include NDV, average/max column length, number of
> nulls, number of trues, number of falses and so on.
> What do you think?
>
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