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Posted to jira@arrow.apache.org by "Andrew Lamb (Jira)" <ji...@apache.org> on 2020/12/09 11:45:00 UTC
[jira] [Resolved] (ARROW-10781) [Rust] [DataFusion] TableProvider
should provide row count statistics
[ https://issues.apache.org/jira/browse/ARROW-10781?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andrew Lamb resolved ARROW-10781.
---------------------------------
Fix Version/s: 3.0.0
Resolution: Fixed
Issue resolved by pull request 8866
[https://github.com/apache/arrow/pull/8866]
> [Rust] [DataFusion] TableProvider should provide row count statistics
> ---------------------------------------------------------------------
>
> Key: ARROW-10781
> URL: https://issues.apache.org/jira/browse/ARROW-10781
> Project: Apache Arrow
> Issue Type: New Feature
> Components: Rust - DataFusion
> Reporter: Andy Grove
> Priority: Major
> Labels: pull-request-available
> Fix For: 3.0.0
>
> Time Spent: 8h 10m
> Remaining Estimate: 0h
>
> In order to start building a cost-based optimizer, we need some statistics about data sources. The most basic statistic would be number of rows.
> I propose that we add a Statistics struct that initially just makes a total row count available but that we can later extend to support more advanced statistics.
> {code:java}
> struct Statistics {
> row_count: Option<usize>
> } {code}
> We can then add a method to TableProvider:
> {code:java}
> trait TableProvider {
> fn statistics() -> Option<Statistics>;
> } {code}
> Statistics should be optional because not all data sources can provide statistics.
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