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https://issues.apache.org/jira/browse/DRILL-7089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16811945#comment-16811945
]
ASF GitHub Bot commented on DRILL-7089:
---------------------------------------
amansinha100 commented on pull request #1728: DRILL-7089: Implement caching for
TableMetadataProvider at query level and adapt statistics to use Drill
metastore API
URL: https://github.com/apache/drill/pull/1728#discussion_r272845347
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/metastore/ColumnStatisticsKind.java
##########
@@ -106,6 +107,53 @@ public boolean isValueStatistic() {
public boolean isExact() {
return true;
}
+ },
+
+ /**
+ * Column statistics kind which represents number of non-null values for the
specific column.
+ */
+ NON_NULL_COUNT(Statistic.NNROWCOUNT) {
+ @Override
+ public Double mergeStatistics(List<? extends ColumnStatistics>
statisticsList) {
+ double nonNullRowCount = 0;
+ for (ColumnStatistics statistics : statisticsList) {
+ Double nnRowCount = (Double) statistics.getStatistic(this);
+ if (nnRowCount != null) {
+ nonNullRowCount += nnRowCount;
+ }
+ }
+ return nonNullRowCount;
+ }
+ },
+
+ /**
+ * Column statistics kind which represents number of distinct values for the
specific column.
+ */
+ NVD(Statistic.NDV) {
+ @Override
+ public Object mergeStatistics(List<? extends ColumnStatistics>
statisticsList) {
+ throw new UnsupportedOperationException("Cannot merge statistics for
NDV");
+ }
+ },
+
+ /**
+ * Column statistics kind which width of the specific column.
+ */
+ AVG_WIDTH(Statistic.AVG_WIDTH) {
+ @Override
+ public Object mergeStatistics(List<? extends ColumnStatistics>
statisticsList) {
+ throw new UnsupportedOperationException("Cannot merge statistics for
avg_width");
+ }
+ },
+
+ /**
+ * Column statistics kind which width of the specific column.
Review comment:
Change to histogram.
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> Implement caching of BaseMetadata classes
> -----------------------------------------
>
> Key: DRILL-7089
> URL: https://issues.apache.org/jira/browse/DRILL-7089
> Project: Apache Drill
> Issue Type: Sub-task
> Affects Versions: 1.16.0
> Reporter: Volodymyr Vysotskyi
> Assignee: Volodymyr Vysotskyi
> Priority: Major
> Fix For: 1.16.0
>
>
> In the scope of DRILL-6852 were introduced new classes for metadata usage.
> These classes may be reused in other GroupScan instances to preserve heap
> usage for the case when metadata is large.
> The idea is to store {{BaseMetadata}} inheritors in {{DrillTable}} and pass
> them to the {{GroupScan}}, so in the scope of the single query, it will be
> possible to reuse them.
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