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https://issues.apache.org/jira/browse/IMPALA-7630?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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bharath v updated IMPALA-7630:
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Description:
The idea is to implement VIRTUAL columns that are computed using other column
values using deterministic expressions. Oracle [1] and MySQL [2] already
support something like this.
Some advantages of having virtual columns
- Simplifies queries that can refer to these columns directly
- Better cardinality estimates for virtual columns based on their pre-computed
stats.
[1] https://oracle-base.com/articles/11g/virtual-columns-11gr1
[2] https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html
> Support GENERATED/VIRTUAL columns in Impala tables
> --------------------------------------------------
>
> Key: IMPALA-7630
> URL: https://issues.apache.org/jira/browse/IMPALA-7630
> Project: IMPALA
> Issue Type: New Feature
> Components: Backend, Frontend
> Affects Versions: Impala 3.1.0
> Reporter: bharath v
> Priority: Major
>
> The idea is to implement VIRTUAL columns that are computed using other column
> values using deterministic expressions. Oracle [1] and MySQL [2] already
> support something like this.
> Some advantages of having virtual columns
> - Simplifies queries that can refer to these columns directly
> - Better cardinality estimates for virtual columns based on their
> pre-computed stats.
> [1] https://oracle-base.com/articles/11g/virtual-columns-11gr1
> [2]
> https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html
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