[ https://issues.apache.org/jira/browse/CASSANDRA-7168?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
C. Scott Andreas updated CASSANDRA-7168: ---------------------------------------- Component/s: Coordination > Add repair aware consistency levels > ----------------------------------- > > Key: CASSANDRA-7168 > URL: https://issues.apache.org/jira/browse/CASSANDRA-7168 > Project: Cassandra > Issue Type: Improvement > Components: Coordination > Reporter: T Jake Luciani > Priority: Major > Labels: performance, repair > Fix For: 4.x > > > With CASSANDRA-5351 and CASSANDRA-2424 I think there is an opportunity to > avoid a lot of extra disk I/O when running queries with higher consistency > levels. > Since repaired data is by definition consistent and we know which sstables > are repaired, we can optimize the read path by having a REPAIRED_QUORUM which > breaks reads into two phases: > > 1) Read from one replica the result from the repaired sstables. > 2) Read from a quorum only the un-repaired data. > For the node performing 1) we can pipeline the call so it's a single hop. > In the long run (assuming data is repaired regularly) we will end up with > much closer to CL.ONE performance while maintaining consistency. > Some things to figure out: > - If repairs fail on some nodes we can have a situation where we don't have > a consistent repaired state across the replicas. > -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org