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From Apache Wiki <>
Subject [Cassandra Wiki] Update of "FAQ" by TylerHobbs
Date Sat, 30 Apr 2011 23:20:31 GMT
Dear Wiki user,

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The "FAQ" page has been changed by TylerHobbs.
The comment on this change is: Grammar/clarity fixes for "bigcommitlog" entry..


  == Commit Log gets very big. Cassandra does not delete "old" commit logs. Why? ==
- You probably got a few Column Families with very low throughput. They will not get flushed
very frequently and the commit log doesnt get deleted. There is one option to work around
the problem: You can set the per-cf-option memtable_flush_after_min. This will flush your
CF at least every x minutes. 60 minutes i a good value to start. To set this via cassandra-cli
+ You probably have one or more Column Families with very low throughput. These will typically
not be flushed by crossing the throughput or operations thresholds, causing old commit segments
to be retained until the memtable_flush_after_min threshold has been crossed. The default
value for this threshold is 60 minutes and may be decreased via cassandra-cli by doing:
- update column family XXX with memtable_flush_after=60;
+ {{{ update column family XXX with memtable_flush_after=YY; }}}
+ where YY is a number of minutes.

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