system.log should show you some warnings about wide rows. Do a grep on system.log for 'Writing large partition' The message could be different for the c* version you're using though. Plus, this doesn't show you all of the large partitions.
There is a nice tool that analyzes sstables and can show the large partitions: https://github.com/tolbertam/sstable-tools By "how to deal with them?" it depends. If you don't need those partitions then you can delete them. You can also use TTL if it fits you or remodel your table to only hold upto 100k rows or 100mb per partition (whichever comes first). If you're going to remodel the table, aim for much less than 100k/100mb per partition. Ali Hubail Confidentiality warning: This message and any attachments are intended only for the persons to whom this message is addressed, are confidential, and may be privileged. If you are not the intended recipient, you are hereby notified that any review, retransmission, conversion to hard copy, copying, modification, circulation or other use of this message and any attachments is strictly prohibited. If you receive this message in error, please notify the sender immediately by return email, and delete this message and any attachments from your system. Petrolink International Limited its subsidiaries, holding companies and affiliates disclaims all responsibility from and accepts no liability whatsoever for the consequences of any unauthorized person acting, or refraining from acting, on any information contained in this message. For security purposes, staff training, to assist in resolving complaints and to improve our customer service, email communications may be monitored and telephone calls may be recorded. shalom sagges <shalomsag...@gmail.com> 04/02/2018 03:57 PM Please respond to user@cassandra.apache.org To user@cassandra.apache.org, cc Subject Large Partitions Hi All, I ran nodetool cfstats (v2.0.14) on a keyspace and found that there are a few large partitions. I assume that since "Compacted partition maximum bytes": 802187438 (~800 MB) and since "Compacted partition mean bytes": 100465 (~100 KB), it means that most partitions are in okay size and only a few are large. Am I assuming correctly? If so, can anyone suggest how to find those large partitions and how to deal with them? (cfstats output below) Thanks! nodetool cfstats keyspace1; Table: table1 SSTable count: 16 Space used (live), bytes: 453844035587 Space used (total), bytes: 453844035587 Off heap memory used (total), bytes: 440787635 SSTable Compression Ratio: 0.17417149031966575 Number of keys (estimate): 33651200 Memtable cell count: 27966 Memtable data size, bytes: 41698140 Memtable switch count: 199727 Local read count: 86494530 Local read latency: 2.646 ms Local write count: 247712138 Local write latency: 0.030 ms Pending tasks: 0 Bloom filter false positives: 2182242 Bloom filter false ratio: 0.02251 Bloom filter space used, bytes: 53135136 Bloom filter off heap memory used, bytes: 53135008 Index summary off heap memory used, bytes: 11560419 Compression metadata off heap memory used, bytes: 376092208 Compacted partition minimum bytes: 373 Compacted partition maximum bytes: 802187438 Compacted partition mean bytes: 100465 Average live cells per slice (last five minutes): 37.0 Average tombstones per slice (last five minutes): 0.0