There can be many root causes. Would need a lot more information such as node hardware specs, cf histograms on the table, tpstats,GC settings (Max heap, parnew, JVM version) and logs with specifically any ERROR, WARN, or GCInspector messages
As a start a simple trace of the query in question is probably good enough. On Dec 22, 2014 10:59 AM, "Paolo Crosato" <paolo.cros...@targaubiest.com> wrote: > Hi, > > I declared this CF: > > CREATE TABLE timesliceunitstate ( > day timestamp, > unitbuckets text, > PRIMARY KEY (day) > ); > > unitbuckets is a text column holding a fairly big amount of data, around > 30 MB of json text per row. > > The table is holding 30 rows, I'm running cassandra 2.0.8 on a 3 nodes > cluster with replication factor of 3, consistency of reads is quorum, so 2 > out of 3 nodes. > > The table has a write hit about every 20 minutes, which updates only one > row, the most recent. > > I had no problem with read queries (I query the table one row at time) > until this morning, when read latency jumped from around 300ms to 20 > seconds for each query. > > I tried repairing the table on all the 3 nodes using range repair without > success, the *Data.db file on the disk is aorund 30 MB, so a bit less than > 1MB for each row. > > I'm using latest version of datastax driver, 2.1. I changed nothing on the > application level since days, so it's not something related to the > applicacation or the driver. > > Is there anyway I can troubleshoot the issue and discover what's making > the table so slow? > > Thanks for any advice, > > Paolo > > -- > Paolo Crosato > Software engineer/Custom Solutions > e-mail: paolo.cros...@targaubiest.com > >
