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From Todd Burruss <>
Subject GCGraceSeconds per ColumnFamily/Keyspace
Date Mon, 12 Jul 2010 23:33:38 GMT
I have two CFs in my keyspace.  one i care about allowing a good amount of time for tombstones
to propagate (GCGraceSeconds large) ... but the other i couldn't care and in fact i want them
gone ASAP so i don't iterate over them.  has any thought been given to making this setting
per Keyspace or per ColumnFamily?

my scenario is that i add columns to rows in one CF, UserData, with logging data or activity,
but we only want to keep, say 5000 columns per user.  So i also store the user's ID in another
CF, PruneCollection, and periodically iterate over it using the IDs found in PruneCollection
to "prune" the columns in UserData - and then immediately delete the ID from PruneCollection.
 if the code is adding, say 50 IDs per second to PruneCollection then the number of deleted
keys starts to build up, forcing my iterator to skip over large amounts of deleted keys. 
With a small GCGraceSeconds these keys are removed nicely, but i can't do that because it
affects the tombstones in UserData as well, which need to be propagated.

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