Github user jinfengni commented on a diff in the pull request:
https://github.com/apache/drill/pull/805#discussion_r109536003
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java
---
@@ -1668,9 +1666,16 @@ public ColumnMetadata_v3(String[] name,
PrimitiveTypeName primitiveType, Object
return nulls;
}
+ /**
+ * Checks that the column chunk has single value.
+ * Returns true if minValue and maxValue are null and
+ * column statistics was available.
+ *
+ * @return true if column has single value
+ */
@Override
public boolean hasSingleValue() {
- return (minValue !=null && maxValue != null &&
minValue.equals(maxValue));
+ return minValue != null ? minValue.equals(maxValue) : (maxValue ==
null && isMetadataSet());
--- End diff --
We probably need better definition of "column has single value", before go
ahead and modify this function. Cases we need consider:
1) minValue / maxValue != null and there is no "null" in the column.
2) minValue / maxValue != null and there is "null" in the column.
3) minValue/maxValue == null, and there is "null" in the column
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