Thanks a lot Jonathan !!! Kannan
________________________________ From: Jonathan Ellis <jbel...@gmail.com> To: user@cassandra.apache.org Sent: Mon, September 13, 2010 4:47:05 PM Subject: Re: Couple of cache related questions On Sun, Sep 12, 2010 at 6:10 PM, kannan chandrasekaran <ckanna...@yahoo.com> wrote: >> 1) What determines the amount of memory used per schema ignoring the >> general >> overhead to get cassandra up and running? Is it just the size of the >> caches >> for the column Family + the memtable size ? > > and the bloom filter and index samples from the sstable files. > > Does that mean that cassandra tries to load the index and filter tables in > memory as well, for each sstable in the keyspace? it means it loads the bloom filter file, and a sample from the index file. > Once the final memtable is flushed to the disk ( assuming no more writes) , > does read path also incur the memory size of the memtable for that > particular CF ? no. > Does cassandra try to preallocate memory after startup for each schema even > if its not used ( not being currently written to or read from) ? no. > If I understand you correctly then I need to make sure that > the sum of sizes of all items in the cache across all the keyspaces + > memtable + bloom filter + index samples < Heap space yes. -- Jonathan Ellis Project Chair, Apache Cassandra co-founder of Riptano, the source for professional Cassandra support http://riptano.com
