I'm fairly certain the write path hits the commit log first, then the memtable.
2010/5/25 Peter Schüller <sc...@spotify.com> > > I have seen several off-hand mentions that writes are inherently faster > than > > reads. Why is this so? > > I believe the primary factor people are referring to is that writes > are faster than reads in terms of disk I/O because writes are > inherently sequential. Writes initially only happen in-memory plus in > a (sequentially written) commit log; when flushed out to an sstable > that is likewise sequential writing. > > Reads on the other hand, to the extent that they go down to disk, will > suffer the usual overhead associated with disk seeks. > > See http://wiki.apache.org/cassandra/ArchitectureInternals for details. > > -- > / Peter Schuller aka scode >
