Hi Jack, I read about arena allocators. So, does allocation happen only for memtables that are active(have atleast 1 update). What happens if the CF is inactive and does not have any updates in the memtable? Will cassandra still allocate 1MB for the CF?
On Fri, Jul 11, 2014 at 5:50 PM, Jack Krupansky <j...@basetechnology.com> wrote: > Technically, key spaces themselves are relatively cheap, so there is no > limit there per se. But... you probably want to put tables in them, which > are not so cheap. Generally, the guidance is for no more than “low > hundreds” of tables, regardless of whether you have one table per key space > or all in one key space. > > If you want to go beyond “low hundreds” of tables, tread carefully. The > official line is that “Although having more than dozens or hundreds of > tables defined is almost certainly a Bad Idea (just as it is a design smell > in a relational database), it's relatively straightforward to allow > disabling the SlabAllocator.” Emphasis on “almost certainly a Bad Idea.” > > See: > https://issues.apache.org/jira/browse/CASSANDRA-5935 > “Allow disabling slab allocation” > > -- Jack Krupansky > > *From:* Sourabh Agrawal <iitr.sour...@gmail.com> > *Sent:* Thursday, July 10, 2014 11:22 PM > *To:* user@cassandra.apache.org > *Subject:* Practical limit to number of keyspaces? > > Hi, > > We are using 2.0.x in production env. Each node has 8G heap. Is there a > practical limit to how many keyspaces I can have? Please note that many > keyspaces remain mostly dormant while others have very high level of > activity. > > -- > Sourabh Agrawal > Bangalore > +91 9945657973 > -- Sourabh Agrawal Bangalore +91 9945657973
