[ https://issues.apache.org/jira/browse/CASSANDRA-15765?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17093980#comment-17093980 ]
Yifan Cai commented on CASSANDRA-15765: --------------------------------------- It is a potential performance issue. Those methods' signatures accepts {{List}}, meanwhile the implementations assume the type of input is {{List}} with {{RandomAccess}}. The current code runs just fine. The input should be all array-based lists, as far as I can see. > Get-by-index introduced in CASSANDRA-15394 could have negative performance > impact on non-RandomAccess List > ---------------------------------------------------------------------------------------------------------- > > Key: CASSANDRA-15765 > URL: https://issues.apache.org/jira/browse/CASSANDRA-15765 > Project: Cassandra > Issue Type: Improvement > Components: Legacy/Core > Reporter: Yifan Cai > Assignee: Yifan Cai > Priority: Normal > > CASSANDRA-15394 replaced the iterator based iteration with the get-by-index > one to avoid allocation iterators. > It works for the lists that support RandomAccess, i.e. the big O of {{get()}} > is {{O(1)}}. > However, it fails when the list does not support RandomAccess. The {{get()}} > method's time complexity can be linear, and it leads to {{O(n^2)}} for the > overall iteration. > The implementation should provide different behaviors based on the property. -- This message was sent by Atlassian Jira (v8.3.4#803005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org