Sounds to me like you're confusing atomicity with isolation. On Thu, Jul 7, 2011 at 2:54 PM, Jeffrey Kesselman <jef...@gmail.com> wrote: > Yup, im even more confused. Lets talk about the model, not the > implementation. > AIUI updates to a row are atomic across all columns in that row at once, > true? > If true then the next question is, does the validation happen inside or > outside of that guarantee, and is the row guaranteed not to change between > validation and update? > If that is *not* the case then it makes a whole class of solutions to > synchronization problems fail and puts my larger project > in serious question. > > On Thu, Jul 7, 2011 at 3:43 PM, Yang <teddyyyy...@gmail.com> wrote: >> >> no , the memtable is a concurrentskiplistmap >> >> insertion can happen in parallel >> >> On Jul 7, 2011 9:24 AM, "Jeffrey Kesselman" <jef...@gmail.com> wrote: >> > This has me more confused. >> > >> > Does this mean that ALL rows on a given node are only updated >> > sequentially, >> > never in parallel? >> > >> > On Thu, Jul 7, 2011 at 3:21 PM, Yang <teddyyyy...@gmail.com> wrote: >> > >> >> just to add onto what jonathan said >> >> >> >> the columns are immutable . if u overwrite/ reconcile a new obj is >> >> created and shoved into the memtable >> >> >> >> there is a shared lock for all writes though which guard against an >> >> exclusive lock on memtable switching/flushing >> >> On Jul 7, 2011 7:51 AM, "A J" <s5a...@gmail.com> wrote: >> >> > Does a write lock: >> >> > 1. Just the columns in question for the specific row in question ? >> >> > 2. The full row in question ? >> >> > 3. The full CF ? >> >> > >> >> > I doubt read does any locks. >> >> > >> >> > Thanks. >> >> >> > >> > >> > >> > -- >> > It's always darkest just before you are eaten by a grue. > > > > -- > It's always darkest just before you are eaten by a grue. >
-- Jonathan Ellis Project Chair, Apache Cassandra co-founder of DataStax, the source for professional Cassandra support http://www.datastax.com
