Not confusing, but assuming a few things. I made a more detailed post in the Datatstax forums.
On Thu, Jul 7, 2011 at 10:27 PM, Jonathan Ellis <jbel...@gmail.com> wrote: > 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 > -- It's always darkest just before you are eaten by a grue.
