On Fri, Nov 5, 2010 at 1:41 PM, Jeremy Davis <email@example.com> wrote:
I saw in the Riptano "Tuning Cassandra" slide deck that the row cache can be detrimental if there are a lot of updates to the cached row. Is this because the cache is not write through, and every update necessitates creation of a new row?
I see there is an open issue: https://issues.apache.org/jira/browse/CASSANDRA-860 for implementing write through in 0.8.
The problem is that if the row is being updated a lot, the cache is turning over quickly, and this exerts GC pressure on the JVM. Even if it were write-through, row cache is probably a bad match for this kind of row, it's much better at mostly static rows. Rely on keycache and OS file cache for these instead.