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https://issues.apache.org/jira/browse/DRILL-7491?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17015586#comment-17015586
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ASF GitHub Bot commented on DRILL-7491:
---------------------------------------
paul-rogers commented on pull request #1955: DRILL-7491: Incorrect count()
returned for complex types in parquet
URL: https://github.com/apache/drill/pull/1955#discussion_r366671949
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/AbstractGroupScanWithMetadata.java
##########
@@ -167,29 +167,46 @@ public boolean isMatchAllMetadata() {
*/
@Override
public long getColumnValueCount(SchemaPath column) {
- long tableRowCount, colNulls;
- Long nulls;
ColumnStatistics<?> columnStats =
getTableMetadata().getColumnStatistics(column);
- ColumnStatistics<?> nonInterestingColStats = null;
- if (columnStats == null) {
- nonInterestingColStats =
getNonInterestingColumnsMetadata().getColumnStatistics(column);
- }
+ ColumnStatistics<?> nonInterestingColStats = columnStats == null
+ ? getNonInterestingColumnsMetadata().getColumnStatistics(column) :
null;
+ long tableRowCount;
if (columnStats != null) {
tableRowCount =
TableStatisticsKind.ROW_COUNT.getValue(getTableMetadata());
} else if (nonInterestingColStats != null) {
tableRowCount =
TableStatisticsKind.ROW_COUNT.getValue(getNonInterestingColumnsMetadata());
Review comment:
Having a hard time understanding this. If a column is uninteresing, we get
the row count from the non-interesting columns metadata. Seems round-about.
Should we get the row count from the table itself? That is, the indirection
through non-interesting columns to get table metadata seems awkward.
Also, if we do have column stats, we get the row count from the table
metadata. This raises the question: by column value count, do we mean NDV
(number of distinct values)? Otherwise, the column value count for top-level
columns is defined as the same as the row count whether the column is
interesting or not.
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> Incorrect count() returned for complex types in parquet
> -------------------------------------------------------
>
> Key: DRILL-7491
> URL: https://issues.apache.org/jira/browse/DRILL-7491
> Project: Apache Drill
> Issue Type: Bug
> Components: Functions - Drill, Functions - Hive, Storage - Parquet
> Affects Versions: 1.16.0, 1.17.0
> Reporter: Igor Guzenko
> Assignee: Igor Guzenko
> Priority: Major
> Labels: ready-to-commit
> Fix For: 1.18.0
>
> Attachments: hive_alltypes.parquet
>
>
> To reproduce use the attached file for {{hive_alltypes.parquet}} (this is
> parquet file generated by Hive) and try count on columns *c13 - c15.* For
> example,
> {code:sql}
> SELECT count(c13) FROM dfs.tmp.`hive_alltypes.parquet`
> {code}
> *Expected result:* {color:green}3 {color}
> *Actual result:* {color:red}0{color}
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