aokolnychyi commented on a change in pull request #2240:
URL: https://github.com/apache/iceberg/pull/2240#discussion_r691628415
##########
File path: core/src/main/java/org/apache/iceberg/util/SortOrderUtil.java
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@@ -64,4 +68,16 @@ static SortOrder buildSortOrder(Schema schema, PartitionSpec
spec, SortOrder sor
return builder.build();
}
+
+ public static Set<String> sortedColumns(SortOrder sortOrder) {
+ if (sortOrder == null) {
+ return Collections.emptySet();
+ } else {
+ return sortOrder.fields().stream()
+ .map(SortField::sourceId)
+ .map(sid -> sortOrder.schema().findColumnName(sid))
Review comment:
After another look with fresh eyes, I don't think my statement above is
accurate. If we sort using an order preserving transform, it means the source
columns are somehow sorted (but may not be perfectly sorted).
For example, sorting by `month(date)`, means our dates are sorted across
months but not necessarily within each month. Still, it probably makes sense to
promote such columns. Identity and truncate transforms are also order
preserving.
@RussellSpitzer @jackye1995, thoughts?
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