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From "Wei Deng (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-12183) compaction_history system table does not capture all historical compaction sessions
Date Tue, 12 Jul 2016 23:43:21 GMT
Wei Deng created CASSANDRA-12183:
------------------------------------

             Summary: compaction_history system table does not capture all historical compaction
sessions
                 Key: CASSANDRA-12183
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12183
             Project: Cassandra
          Issue Type: Bug
          Components: Compaction, Observability
            Reporter: Wei Deng


It appears that some compaction sessions are not recorded in system.compaction_history table
after the compaction session successfully finishes.

The following is an example (test by simply running +cassandra-stress write n=100000000+):

{noformat}
automaton@wdengdse50google-98425b985-3:~$ nodetool compactionstats
pending tasks: 46
                                     id   compaction type    keyspace       table    completed
       total    unit   progress
   fa8a4f30-4884-11e6-b916-1dbd340a212f        Compaction   keyspace1   standard1   4233184044
  4774209875   bytes     88.67%
   91e30d21-4887-11e6-b916-1dbd340a212f        Compaction   keyspace1   standard1    836983029
   889773060   bytes     94.07%
Active compaction remaining time :   0h00m35s
automaton@wdengdse50google-98425b985-3:~$ nodetool compactionstats
pending tasks: 47
                                     id   compaction type    keyspace       table    completed
       total    unit   progress
   fa8a4f30-4884-11e6-b916-1dbd340a212f        Compaction   keyspace1   standard1   4353251539
  4774209875   bytes     91.18%
   28359094-4888-11e6-b916-1dbd340a212f        Compaction   keyspace1   standard1     49732274
  4071652280   bytes      1.22%
Active compaction remaining time :   0h04m24s
{noformat}

At this point you know the previous compaction session 91e30d21-4887-11e6-b916-1dbd340a212f
finished and confirmation can be found from debug.log

{noformat}
automaton@wdengdse50google-98425b985-3:~$ grep 91e30d21-4887-11e6-b916-1dbd340a212f /var/log/cassandra/debug.log
DEBUG [CompactionExecutor:4] 2016-07-12 23:22:58,674  CompactionTask.java:146 - Compacting
(91e30d21-4887-11e6-b916-1dbd340a212f) [/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-290-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-279-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-281-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-280-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-284-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-283-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-287-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-292-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-286-big-Data.db:level=0,
/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-289-big-Data.db:level=0,
]
DEBUG [CompactionExecutor:4] 2016-07-12 23:26:56,054  CompactionTask.java:217 - Compacted
(91e30d21-4887-11e6-b916-1dbd340a212f) 10 sstables to [/var/lib/cassandra/data/keyspace1/standard1-9c02e9c1487c11e6b9161dbd340a212f/mb-293-big,]
to level=0.  889,773,060 bytes to 890,473,350 (~100% of original) in 237,365ms = 3.577703MB/s.
 0 total partitions merged to 3,871,921.  Partition merge counts were {1:3871921, }
{noformat}

However, if you query system.compaction_history table or run "nodetool compactionhistory |
grep 91e30d21-4887-11e6-b916-1dbd340a212f" you will get nothing:

{noformat}
automaton@wdengdse50google-98425b985-3:~$ cqlsh -u cassandra
Password:
Connected to dse50 at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.0.7.1158 | DSE 5.0.0 | CQL spec 3.4.0 | Native protocol v4]
Use HELP for help.
cassandra@cqlsh> select * from system.compaction_history where id=91e30d21-4887-11e6-b916-1dbd340a212f;

 id | bytes_in | bytes_out | columnfamily_name | compacted_at | keyspace_name | rows_merged
----+----------+-----------+-------------------+--------------+---------------+-------------

(0 rows)

automaton@wdengdse50google-98425b985-3:~$ nodetool flush system
automaton@wdengdse50google-98425b985-3:~$ nodetool compactionhistory | grep 91e30d21-4887-11e6-b916-1dbd340a212f
{noformat}



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