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Kurt Greaves commented on CASSANDRA-10792: ------------------------------------------ This was solved in CASSANDRA-11529. Marking as duplicate but speak up if I'm missing something. > Make warning level for count of partitions in unlogged BatchStatement > configurable. > ----------------------------------------------------------------------------------- > > Key: CASSANDRA-10792 > URL: https://issues.apache.org/jira/browse/CASSANDRA-10792 > Project: Cassandra > Issue Type: Improvement > Components: Configuration, CQL > Environment: CentOS, JDK 1.7, cluster of servers with 32 CPU each. > Reporter: Pawel Matras > Priority: Minor > Fix For: 4.x > > > Currently mutations for only one partition are allowed in BatchStatement. > This amount is hard coded and not configurable as e.g. batch size. > General suggestion looks to be to consider multi partition unlogged batch > statements as distributed anti pattern. As cure async inserts are proposed. > Proposal might be OK if one consider only cassandra side of the system. > If a complete system have to share the same hardware things does not look so > obvious any more. When cassandra shares the same hardware with other also > clustered components lots of small async inserts become another well known > distributed anti pattern. > In our case changing from unlogged batches to async inserts destabilize the > system as async inserts require amounts of interrupts per second and context > switches per second beyond what hardware can handle. With replica aware > unlogged batches these parameters are at 40% of hardware limits and the > system as a whole runs stable without visible hotspots (cassandra metrics > looks almost the same on all nodes). > Unfortunately latest versions (we switched from 2.0.6 to 2.2.1) of cassandra > log lots of warnings of type "Unlogged batch covering NN partitions detected > against table XXX...". I found two workarounds to avoid this warning. The one > is to use logged batches. But they generate 20% more interrupts and context > switches and 400% more network load. The other way is more a hack and uses > filtering features of logging framework and suppresses the warning just > before it get logged. > So my suggestion is to allow users of cassandra to decide by configuration if > they consider unlogged batches antipattern or not. This is partially done > with the size of the batch, where size is configurable and not hardcoded to 5 > kB. > It would be fine to stay consistent on this and let the user configure > mutations for how many partitions to allow. > Of course there are several other solutions possible here, probably more > costly. E.g warning could be produced only if batch is not token/replica > aware. -- This message was sent by Atlassian JIRA (v6.4.14#64029) --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org