This documentation from Datastax may be helpful to understand the purpose of memtables and sstables. http://docs.datastax.com/en/cassandra/2.0/cassandra/dml/dml_write_path_c.html
Ray On Sat, Sep 5, 2015 at 10:36 AM Anuj Wadehra <[email protected]> wrote: > Memtables are for storing writes in memory till they are flushed to disk > as sstables and once flushed, space gets released from commit logs too.. If > your are updating some columns only that data would be there in memtables > not entire row..Dont think of memtables as row cache.. > > This is my understanding..Anyone is free to add/correct info provided... > > > Anuj > > Sent from Yahoo Mail on Android > <https://overview.mail.yahoo.com/mobile/?.src=Android> > ------------------------------ > *From*:"Jim Shi" <[email protected]> > *Date*:Sat, 5 Sep, 2015 at 10:11 am > *Subject*:memtable and sstables > > Hi, I have a question: > > in a read operation, why data in memtable needs merges with data in > sstables? > > I thought if a key exists in memtable, it has all the data related to the > key. Is this assumption not correct? >
