amansinha100 commented on a change in pull request #1771: DRILL-7199: Optimize
population of metadata for non-interesting columns
URL: https://github.com/apache/drill/pull/1771#discussion_r280187957
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/physical/base/AbstractGroupScanWithMetadata.java
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@@ -146,15 +148,23 @@ public boolean isMatchAllMetadata() {
*/
@Override
public long getColumnValueCount(SchemaPath column) {
- long tableRowCount = (long)
TableStatisticsKind.ROW_COUNT.getValue(getTableMetadata());
+ long tableRowCount, colNulls;
+ Long nulls;
ColumnStatistics columnStats =
getTableMetadata().getColumnStatistics(column);
- long colNulls;
+ ColumnStatistics nonInterestingColStats =
getNonInterestingColumnsMetadata().getColumnStatistics(column);
+
if (columnStats != null) {
- Long nulls = (Long)
columnStats.getStatistic(ColumnStatisticsKind.NULLS_COUNT);
- colNulls = nulls != null ? nulls : GroupScan.NO_COLUMN_STATS;
+ tableRowCount = (long)
TableStatisticsKind.ROW_COUNT.getValue(getTableMetadata());
+ } else if (nonInterestingColStats != null) {
Review comment:
Since only one of `columnStats` (btw, let's call it `interestingColStats` to
be consistent) or `nonInterestingColStats` will be non-null, we should ideally
invoke `getNonInterestingColumnsMetadata()` only if the `columnStats` is
null...otherwise the second call is redundant. So, something like:
`ColumnStatistics interestingColStats =
getTableMetadata().getColumnStatistics(column);`
`ColumnStatistics nonInterestingColStats = null;`
`if (interestingColStats == null) {`
`nonInterestingColStats =
getNonInterestingColumnsMetadata().getColumnStatistics(column);`
`}`
Also, for the last `else` case, add a comment that the `return 0` is for
non-existing columns.
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