Github user vvysotskyi commented on a diff in the pull request:
https://github.com/apache/drill/pull/805#discussion_r126438246
--- Diff:
exec/java-exec/src/main/java/org/apache/drill/exec/store/parquet/Metadata.java
---
@@ -1008,8 +1008,24 @@ public void setMax(Object max) {
return nulls;
}
- @Override public boolean hasSingleValue() {
- return (max != null && min != null && max.equals(min));
+ /**
+ * Checks that the column chunk has single value.
+ * Returns true if min and max are the same, but not null.
+ * Returns true if min and max are null and the number of null values
+ * in the column chunk is greater than 0.
+ *
+ * @return true if column has single value
--- End diff --
Thanks for such detailed analysis. This bug is also reproduced on master
version, but it appears due to the wrong result of this method. Added a
comparison of `nulls` with rows count to fix this bug and allow to return true
for the case when field has only nulls.
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