Are you frequently updating same rows ? What is the memtable flush size ? can you post the table create query here in please.
On Thu, Mar 26, 2015 at 1:21 PM, Dave Galbraith <david92galbra...@gmail.com> wrote: > Hey! So I'm running Cassandra 2.1.2 and using the > SizeTieredCompactionStrategy. I'm doing about 3k writes/sec on a single > node. My read performance is terrible, all my queries just time out. So I > do nodetool cfstats: > > Read Count: 42071 > Read Latency: 67.47804242827601 ms. > Write Count: 131964300 > Write Latency: 0.011721604274792501 ms. > Pending Flushes: 0 > Table: metrics16513 > SSTable count: 641 > Space used (live): 6366740812 > Space used (total): 6366740812 > Space used by snapshots (total): 0 > SSTable Compression Ratio: 0.25272488401992765 > Memtable cell count: 0 > Memtable data size: 0 > Memtable switch count: 1016 > Local read count: 42071 > Local read latency: 67.479 ms > Local write count: 131964300 > Local write latency: 0.012 ms > Pending flushes: 0 > Bloom filter false positives: 994 > Bloom filter false ratio: 0.00000 > Bloom filter space used: 37840376 > Compacted partition minimum bytes: 104 > Compacted partition maximum bytes: 24601 > Compacted partition mean bytes: 255 > Average live cells per slice (last five minutes): > 111.67243951154147 > Maximum live cells per slice (last five minutes): 1588.0 > Average tombstones per slice (last five minutes): 0.0 > Maximum tombstones per slice (last five minutes): 0.0 > > and nodetool cfhistograms: > > Percentile SSTables Write Latency Read Latency Partition > Size Cell Count > (micros) (micros) > (bytes) > 50% 46.00 6.99 154844.95 > 149 1 > 75% 430.00 8.53 3518837.53 > 179 1 > 95% 430.00 11.32 7252897.25 > 215 2 > 98% 430.00 15.54 22103886.34 > 215 3 > 99% 430.00 29.86 22290608.19 > 1597 50 > Min 0.00 1.66 26.91 > 104 0 > Max 430.00 269795.38 27311364.89 > 24601 924 > > Gross!! There are 641 SSTables in there, and all my reads are hitting > hundreds of them and timing out. How could this possibly have happened, and > what can I do about it? Nodetool compactionstats says pending tasks: 0, by > the way. Thanks! >
