> CQL will read everything into List to make latter a count. From 1.0 onwards count paginated reading the columns. What version are you on ?
https://issues.apache.org/jira/browse/CASSANDRA-2894 Cheers ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 26/09/2012, at 8:26 PM, Віталій Тимчишин <tiv...@gmail.com> wrote: > Actually an easy way to put cassandra down is > select count(*) from A limit 10000000 > CQL will read everything into List to make latter a count. > > 2012/9/26 aaron morton <aa...@thelastpickle.com> > Can you provide some information on the queries and the size of the data they > traversed ? > > The default maximum size for a single thrift message is 16MB, was it larger > than that ? > https://github.com/apache/cassandra/blob/trunk/conf/cassandra.yaml#L375 > > Cheers > > > On 25/09/2012, at 8:33 AM, Bryce Godfrey <bryce.godf...@azaleos.com> wrote: > >> Is there anything I can do on the configuration side to prevent nodes from >> going OOM due to queries that will read large amounts of data and exceed the >> heap available? >> >> For the past few days of we had some nodes consistently freezing/crashing >> with OOM. We got a heap dump into MAT and figured out the nodes were dying >> due to some queries for a few extremely large data sets. Tracked it back to >> an app that just didn’t prevent users from doing these large queries, but it >> seems like Cassandra could be smart enough to guard against this type of >> thing? >> >> Basically some kind of setting like “if the data to satisfy query > >> available heap then throw an error to the caller and about query”. I would >> much rather return errors to clients then crash a node, as the error is >> easier to track down that way and resolve. >> >> Thanks. > > > > > -- > Best regards, > Vitalii Tymchyshyn
