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https://issues.apache.org/jira/browse/DRILL-6101?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16566166#comment-16566166
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ASF GitHub Bot commented on DRILL-6101:
---------------------------------------
ilooner commented on a change in pull request #1414: DRILL-6101: Optimized
implicit columns handling within scanner
URL: https://github.com/apache/drill/pull/1414#discussion_r207013797
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillScanRel.java
##########
@@ -89,7 +90,7 @@ public DrillScanRel(final RelOptCluster cluster, final
RelTraitSet traits,
this.groupScan = drillTable.getGroupScan().clone(this.columns);
} catch (final IOException e) {
throw new DrillRuntimeException("Failure creating scan.", e);
- }
+ }
Review comment:
minor nitpick. Indentation for this is wrong.
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> 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
>
> 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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