leventov commented on a change in pull request #7185: Avoid many unnecessary materializations of collections of 'all segments in cluster' cardinality URL: https://github.com/apache/incubator-druid/pull/7185#discussion_r264413165
########## File path: server/src/main/java/org/apache/druid/metadata/MetadataSegmentManager.java ########## @@ -59,6 +60,8 @@ Collection<ImmutableDruidDataSource> getDataSources(); + Iterable<DataSegment> iterateAllSegments(); Review comment: Creation of the iterable is cheap, but the creation of the underlying *iteration* is not cheap. This method discourages iterating twice on the result, and, in fact, even storing the result in a variable, but rather immediately consuming it, as it happens in all use cases: they look either like ```java for (DataSegment s : iterateAllSegments()) { .. } ``` or ```java iterateAllSegments().forEach(s -> ...); ``` or feeded into `Iterables.transform()`, which happens in `DruidCoordinatorSegmentInfoLoader`. I think the prefix `iterate` reflects this sense of discouragement well. People may feel a little uncomfortable storing an iterable returned from such method in a variable, but the constructions above look perfectly OK. `getIterable()` doesn't such sense of uncomfortableness. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@druid.apache.org For additional commands, e-mail: commits-h...@druid.apache.org