If you notice an
increase
in the amount of
data
that Cassandra stores in SSTables, or if you receive error messages
about failed compactions, check the time of the last successful
compaction for selected SSTables.
Unsuccessful compaction might cause the
disk
that Cassandra uses to run out of free space.
-
In
the nodetool utility, run the
nodetool compactionhistory
command.
Result: Nodetool returns a list of successfully completed compaction operations
that is seven columns wide. The first three columns display the ID, keyspace
name, and the table name of the compacted
SSTable:
Compaction History:
id keyspace_name columnfamily_name
7df0cad0-40f1-11ea-b458-8f3aac917931 system sstable_activity
bd7e3b80-40e0-11ea-b458-8f3aac917931 system size_estimates
589f9b30-40d8-11ea-b458-8f3aac917931 system sstable_activity
9547ed50-40c7-11ea-b458-8f3aac917931 system size_estimates
3352d860-40bf-11ea-b458-8f3aac917931 system sstable_activity
6ff33b40-40ae-11ea-b458-8f3aac917931 system size_estimates
0e0f8b70-40a6-11ea-b458-8f3aac917931 system sstable_activity
The
next four columns display the time of the compaction, the size of the SSTable
before and after compaction, and the number of merged
partitions.
compacted_at bytes_in bytes_out rows_merged
2020-01-27T11:40:53.245 5465 1311 {1:12, 4:34}
2020-01-27T09:40:58.424 1074759 266555 {4:9}
2020-01-27T08:40:53.219 5389 1314 {1:8, 4:34}
2020-01-27T06:40:53.541 1074527 266566 {4:9}
2020-01-27T05:40:53.222 5463 1314 {1:12, 4:34}
2020-01-27T03:40:53.492 1075043 266539 {4:9}
-
In the
compacted_at column, verify the last time a successful
compaction was performed for the SSTables that experience an increase in data
size, or are the subject of error messages.
-
If the amount of time that elapsed from the last successful compaction for the
selected SSTables is significantly higher than for other SSTables,
investigate
the source of the
problem,
for example, by performing other Cassandra troubleshooting
procedures.
For more information, see the Troubleshooting section of the
Apache Cassandra documentation.