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https://issues.apache.org/jira/browse/DRILL-6101?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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salim achouche updated DRILL-6101:
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Fix Version/s: 1.15.0
> Optimize Implicit Columns Processing
> ------------------------------------
>
> Key: DRILL-6101
> URL: https://issues.apache.org/jira/browse/DRILL-6101
> Project: Apache Drill
> Issue Type: Improvement
> Components: Execution - Relational Operators
> Affects Versions: 1.12.0
> Reporter: salim achouche
> Assignee: salim achouche
> Priority: Critical
> Labels: ready-to-commit
> Fix For: 1.15.0
>
>
> Problem Description -
> * Apache Drill allows users to specify columns even for SELECT STAR queries
> * From my discussion with [~paul-rogers], Apache Calcite has a limitation
> where the, extra columns are not provided
> * The workaround has been to always include all implicit columns for SELECT
> STAR queries
> * Unfortunately, the current implementation is very inefficient as implicit
> column values get duplicated; this leads to substantial performance
> degradation when the number of rows are large
> Suggested Optimization -
> * The NullableVarChar vector should be enhanced to efficiently store
> duplicate values
> * This will not only address the current Calcite limitations (for SELECT
> STAR queries) but also optimize all queries with implicit columns
>
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