Sorry for the confusion. That was for the OP. I wrote it quickly right after waking up.
What I'm asking is why does the OP want to keep his data in the memtable exclusively? If the goal is to "make reads fast", then just turn on row caching. If there's so little data that it fits in memory (300MB), and there aren't going to be any writes past the initial small dataset, why use Cassandra? It sounds like the wrong tool for this job. Sounds like something that could easily be stored in S3 and loaded in memory when the app is fired up. On Thu, May 25, 2017 at 8:06 AM Avi Kivity <a...@scylladb.com> wrote: > Not sure whether you're asking me or the original poster, but the more > times data gets overwritten in a memtable, the less it has to be compacted > later on (and even without overwrites, larger memtables result in less > compaction). > > On 05/25/2017 05:59 PM, Jonathan Haddad wrote: > > Why do you think keeping your data in the memtable is a what you need to > do? > On Thu, May 25, 2017 at 7:16 AM Avi Kivity <a...@scylladb.com> wrote: > >> Then it doesn't have to (it still may, for other reasons). >> >> On 05/25/2017 05:11 PM, preetika tyagi wrote: >> >> What if the commit log is disabled? >> >> On May 25, 2017 4:31 AM, "Avi Kivity" <a...@scylladb.com> wrote: >> >>> Cassandra has to flush the memtable occasionally, or the commit log >>> grows without bounds. >>> >>> On 05/25/2017 03:42 AM, preetika tyagi wrote: >>> >>> Hi, >>> >>> I'm running Cassandra with a very small dataset so that the data can >>> exist on memtable only. Below are my configurations: >>> >>> In jvm.options: >>> >>> -Xms4G >>> -Xmx4G >>> >>> In cassandra.yaml, >>> >>> memtable_cleanup_threshold: 0.50 >>> memtable_allocation_type: heap_buffers >>> >>> As per the documentation in cassandra.yaml, the >>> *memtable_heap_space_in_mb* and *memtable_heap_space_in_mb* will be set >>> of 1/4 of heap size i.e. 1000MB >>> >>> According to the documentation here ( >>> http://docs.datastax.com/en/cassandra/3.0/cassandra/configuration/configCassandra_yaml.html#configCassandra_yaml__memtable_cleanup_threshold), >>> the memtable flush will trigger if the total size of memtabl(s) goes beyond >>> (1000+1000)*0.50=1000MB. >>> >>> Now if I perform several write requests which results in almost ~300MB >>> of the data, memtable still gets flushed since I see sstables being created >>> on file system (Data.db etc.) and I don't understand why. >>> >>> Could anyone explain this behavior and point out if I'm missing >>> something here? >>> >>> Thanks, >>> >>> Preetika >>> >>> >>> >> >
