I don't have the additional hardware to try to isolate this issue atm, so I decided to push some code that performs 20% of reads directly from cassandra. The cache hit rate has gone up to about 88% now and it's still climbing, albeit slowly. There remains plenty of free cache space.
Hi James,I don't know how to get the below statistics data and calculate the access times (read/write in ms) in your previous mails. Can you explain a little? Iike to work on it also.CDOn Thu, Apr 1, 2010 at 4:15 AM, Jonathan Ellis <firstname.lastname@example.org> wrote:
On Wed, Mar 31, 2010 at 6:21 PM, James Golick <email@example.com> wrote:> Column Family: Events
> Keyspace: ActivityFeed
> Read Count: 699443
> Read Latency: 16.11017477192566 ms.
> Read Count: 232378
> Read Latency: 0.396 ms.
> Row cache capacity: 500000This says that
> Row cache size: 62768
> Row cache hit rate: 0.007716049382716049
- recent queries to Events are much faster than the lifetime average
for your Keyspace
- even though you have almost no row cache hits (~1700 out of 232000 reads)
Not sure what to make of that, tbh. If it were me I would try to
reproduce on a test machine w/o all that pesky live traffic confusing