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From Jeffrey Kesselman <jef...@gmail.com>
Subject Re: What does a write lock ?
Date Thu, 07 Jul 2011 19:54:40 GMT
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 <teddyyyy123@gmail.com> wrote:

> no , the memtable is a concurrentskiplistmap
>
> insertion can happen in parallel
> On Jul 7, 2011 9:24 AM, "Jeffrey Kesselman" <jeffpk@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 <teddyyyy123@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" <s5alye@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.

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