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RowBasedGrouperHelper: Set hasMultipleValues = false in capabilities. (#11954) 

Useful because it enables anything that consumes groupBy results to
potentially operate more efficiently.
This commit is contained in:
Gian Merlino 2021-11-24 13:14:58 -08:00 committed by GitHub
parent 5e168b861a
commit 12e2228510
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1 changed files with 20 additions and 1 deletions
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21
processing/src/main/java/org/apache/druid/query/groupby/epinephelinae/RowBasedGrouperHelper.java
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@ -60,6 +60,7 @@ import org.apache.druid.query.ordering.StringComparators;
import org.apache.druid.segment.BaseDoubleColumnValueSelector;
import org.apache.druid.segment.BaseFloatColumnValueSelector;
import org.apache.druid.segment.BaseLongColumnValueSelector;
import org.apache.druid.segment.ColumnInspector;
import org.apache.druid.segment.ColumnSelectorFactory;
import org.apache.druid.segment.ColumnValueSelector;
import org.apache.druid.segment.DimensionHandlerUtils;
@ -67,6 +68,7 @@ import org.apache.druid.segment.DimensionSelector;
import org.apache.druid.segment.RowAdapter;
import org.apache.druid.segment.RowBasedColumnSelectorFactory;
import org.apache.druid.segment.column.ColumnCapabilities;
import org.apache.druid.segment.column.ColumnCapabilitiesImpl;
import org.apache.druid.segment.column.ColumnType;
import org.apache.druid.segment.column.RowSignature;
import org.apache.druid.segment.column.ValueType;
@ -381,10 +383,27 @@ public class RowBasedGrouperHelper
}
};
// Decorate "signature" so that it returns hasMultipleValues = false. (groupBy does not return multiple values.)
final ColumnInspector decoratedSignature = new ColumnInspector()
{
@Nullable
@Override
public ColumnCapabilities getColumnCapabilities(String column)
{
final ColumnCapabilities baseCapabilities = signature.getColumnCapabilities(column);
if (baseCapabilities == null || baseCapabilities.hasMultipleValues().isFalse()) {
return baseCapabilities;
} else {
return ColumnCapabilitiesImpl.copyOf(baseCapabilities).setHasMultipleValues(false);
}
}
};
return RowBasedColumnSelectorFactory.create(
adapter,
supplier::get,
() -> signature,
() -> decoratedSignature,
false
);
}