Re: Key cache size

not be fully populated, we have set the > key cache size to 1024M. > > key_cache_size_in_mb: 1024 > > But none of nodes showed the cache capacity is 1G, we have recently > upgraded to 1.2.5, could be an issue in that version? > > Token: (invoke with -T

Key cache size

We noticed that key cache could not be fully populated, we have set the key cache size to 1024M. key_cache_size_in_mb: 1024 But none of nodes showed the cache capacity is 1G, we have recently upgraded to 1.2.5, could be an issue in that version? Token: (invoke with -T/--tokens to

Re: key cache size

This is the key cache entry https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/cache/KeyCacheKey.java Note that the Descriptor is re-used. If you want to see key cache metrics, including bytes used, use nodetool info. Cheers - Aaron Morton Freelance

key cache size

Hi - What is the approximate overhead of the key cache ? Say each key is 50 bytes. What would be the overhead for this key in the key cache ? Thanks, Kanwar

Re: key cache size in mb = 0 doesn't work?

Thank you very much Andras. I will try MX4J tomorrow. Also thanks for the pointers on nodetool. I just poked around a bit, and found that "info" would give you the cache statistics, and there are also "invalidatekeycache" and "invalidaterowcache". I think these are exactly what I need. -- Y.

Re: key cache size in mb = 0 doesn't work?

If its the RMI horror ( registry port + actual port ) you are worried about, enabling MX4J in cassandra-env.sh for the HTTP transport ( http://wiki.apache.org/cassandra/Operations#Monitoring_with_MX4J ) could help although i never used it myself. Or you can just throw in the Jolokia JVM agent h

Re: key cache size in mb = 0 doesn't work?

Interesting -- I completely overlooked the OS cache aspect, but how long does the OS keep cached pages? It seems they reside in memory for 4 hours at least (which happens to be the default time for key cache).. The CF has over 2.6 million rows, and I am only fetching a random set of 5000 each time

Re: key cache size in mb = 0 doesn't work?

SSTables in http://en.wikipedia.org/wiki/Page_cache maybe? How many rows do you have in this CF? Are you getting all columns? What do the cassandra.db mbeans say ( hit ratio, cache requests, items etc ) regards, Andras On 27 Nov 2012, at 04:12, Yiming Sun wrote: > Hi, > > I am carrying out s

key cache size in mb = 0 doesn't work?

Hi, I am carrying out some performance test against a 6-node cassandra cluster (v1.1.0), and need to disable the key cache entirely as one of the scenarios. However, by setting key_cache_size_in_mb to 0, I am still seeing caching effects. For example, when I fetch a set of 5000 rows, the first t

Re: key cache size calculation

On Wed, Apr 4, 2012 at 8:04 AM, aaron morton wrote: > It depends on the workload. > > Increase the cache size until you see the hit rate decrease, or see it > create memory pressure. Watch the logs for messages that the caches have > been decreased. > > Take a look at the Recent Read Latency for t

Re: key cache size calculation

It depends on the workload. Increase the cache size until you see the hit rate decrease, or see it create memory pressure. Watch the logs for messages that the caches have been decreased. Take a look at the Recent Read Latency for the CF. This is how long it takes to actually read data on th

Re: key cache size calculation

On Tue, Apr 3, 2012 at 11:49 AM, aaron morton wrote: > Take a look at the key cache hit rate in nodetool cfstats. > > One approach is to increase the cache size until you do not see a matching > increase in the hit rate. > Thanks Aaron, what do you think will be the ideal cache hit ratio where w

Re: key cache size calculation

Take a look at the key cache hit rate in nodetool cfstats. One approach is to increase the cache size until you do not see a matching increase in the hit rate. > Is there a limit to key cache size? I know that is all taken from heap but > how much max we can go with setting the key

key cache size calculation

Hi guys, We are calculating key cache size right now. There is this column family with ~ 100 million columns and right now we have the cache size set at 2 million. I suspect that the active data we got is not all fitting in the 2 million cache size and we at times are getting query execution

Re: Key cache size is 0 but .75 hit rate

> I need to set my key cache size properly but am not sure how to set it if > each > key cached is stored in the key cache 2 or 3 times. I'd really appreciate > any > insight into how this works. > Thanks! > Julie > > I actually still have this question b

Key cache size seems to be double what I would expect

multiple times. The key cache size is 0 when I get started and I expect it to go to 1 and stay at 1 on all the replication nodes containing the key '500'. But the key cache size becomes 2 and even 3, which I don't understand. Here's what I did. (Note: I restarted server4 pri