No. Consider a scenario where you supply a timestamp a week in the future, flush it to sstable, and then do a write, with the current timestamp. The record in disk will have a timestamp greater than the one in the memtable.
On Wed, Oct 22, 2014 at 9:18 AM, Donald Smith < donald.sm...@audiencescience.com> wrote: > Question about the read path in cassandra. If a partition/row is in the > Memtable and is being actively written to by other clients, will a READ of > that partition also have to hit SStables on disk (or in the page > cache)? Or can it be serviced entirely from the Memtable? > > > > If you select all columns (e.g., “*select * from ….*”) then I can > imagine that cassandra would need to merge whatever columns are in the > Memtable with what’s in SStables on disk. > > > > But if you select a single column (e.g., “*select Name from …. where id= > …*.”) and if that column is in the Memtable, I’d hope cassandra could > skip checking the disk. Can it do this optimization? > > > > Thanks, Don > > > > *Donald A. Smith* | Senior Software Engineer > P: 425.201.3900 x 3866 > C: (206) 819-5965 > F: (646) 443-2333 > dona...@audiencescience.com > > > [image: AudienceScience] > > > -- Jon Haddad http://www.rustyrazorblade.com twitter: rustyrazorblade
