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From Apache Wiki <>
Subject [Couchdb Wiki] Update of "Compaction" by sergeyk
Date Thu, 12 Jun 2008 19:34:15 GMT
Dear Wiki user,

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The following page has been changed by sergeyk:

The comment on the change is:
Added "Additional Information" about Compaction during full capacity write load.

  The compact_running key will be set to true during compaction.
+ === Additional Information ===
+ Note, it is not a good idea to attempt compaction on a database is near full capacity for
its write load. The problem is the compaction process may never catch up with the writes if
they never let up, and eventually it will run out of disk space.
+ Compaction should be attempted when the write load is less than full capacity. Read load
won't affect its ability to complete however.
+ CouchDB works like this to have the least impact possible on clients,  the database remains
online and fully functional to readers and  
+ writers. It is a design limitation that database compaction can't complete when at capacity
for write load, however it is unreasonable to schedule compactions during off-peak hours either.

+ In a clustered environment the write load can switched off for any node during compaction
and brought back up to date with  
+ replication once complete. 
+ In the future, a single couchdb node can be changed to stop or fail other updates if the
write load is too heavy for it to complete in a  reasonable time.

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