[ https://issues.apache.org/jira/browse/CASSANDRA-2540?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Peter Schuller reassigned CASSANDRA-2540: ----------------------------------------- Assignee: Peter Schuller > Data reads by default > --------------------- > > Key: CASSANDRA-2540 > URL: https://issues.apache.org/jira/browse/CASSANDRA-2540 > Project: Cassandra > Issue Type: Wish > Reporter: Stu Hood > Assignee: Peter Schuller > Priority: Minor > > The intention of digest vs data reads is to save bandwidth in the read path > at the cost of latency, but I expect that this has been a premature > optimization. > * Data requested by a read will often be within an order of magnitude of the > digest size, and a failed digest means extra roundtrips, more bandwidth > * The [digest reads but not your data > read|https://issues.apache.org/jira/browse/CASSANDRA-2282?focusedCommentId=13004656&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-13004656] > problem means failing QUORUM reads because a single node is unavailable, and > would require eagerly re-requesting at some fraction of your timeout > * Saving bandwidth in cross datacenter usecases comes at huge cost to > latency, but since both constraints change proportionally (enough), the > tradeoff is not clear > Some options: > # Add an option to use digest reads > # Remove digest reads entirely (and/or punt and make them a runtime > optimization based on data size in the future) > # Continue to use digest reads, but send them to {{N - R}} nodes for > (somewhat) more predicatable behavior with QUORUM > \\ > The outcome of data-reads-by-default should be significantly improved > latency, with a moderate increase in bandwidth usage for large reads. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira