Oh cool :)

Thanks!

I have one more question. Does Hypertable support stored procedures
(procedures = C++ code)?

(I am really sorry for asking questions in bits and pieces.)

On Mar 4, 11:12 pm, Doug Judd <[email protected]> wrote:
> Hypertable is designed in such a way that it could support row level
> transactions.  We currently do not have any transaction API.  The row would
> be all cells with the same row key (like Bigtable).
>
> - Doug
>
> On Thu, Mar 4, 2010 at 1:34 AM, Harshada <[email protected]> wrote:
> > Thanks Doug.
>
> > The previous discussion suggests that-> Hypertable provides row level
> > transactions. (i.e. the consistency is provided at the level of a row
> > --correct me if I am wrong)
> > Here, what does a row mean? The complete row corresponding to a single
> > key i.e. all the columns and all the revisions (like BigTable) or a
> > key and one particular version(timestamp).
>
> > On Feb 2, 8:17 pm, Doug Judd <[email protected]> wrote:
> > > Hi Harshada,
>
> > > Hypertable currently doesn't support ACID transactions.  We've carefully
> > > designed the system so that it could support transactions in the future.
> > > All updates go into a commit log in the DFS for durability.  Each cell
> > has a
> > > 64-bit revision number associated with it.  We use this revision number
> > for
> > > snapshot isolation, to support Multi-version concurrency control (MVCC).
> > > It's possible for the revision number to be supplied with inserts and
> > > queries.  We envision some day building a transaction monitor that sits
> > in
> > > front of a Hypertable cluster to provide distributed transactions.
>
> > > It's also fairly simple to provide row-level transactions.  All of the
> > data
> > > for a given row resides in the same range.  This allows us to easily
> > build
> > > row-level transaction mechanism.  On our near term roadmap, we plan to
> > add
> > > support for integer counters and an atomic increment operation, which is
> > > essentially a specialized transaction.  We may build that on top of a
> > more
> > > generalized row-level read-modify-write mechanism as described in the
> > > Bigtable paper.
>
> > > Is there a specific transaction use case that you would like to see
> > > supported?
>
> > > - Doug
>
> > > On Mon, Feb 1, 2010 at 9:20 PM, Harshada <[email protected]>
> > wrote:
> > > > Hi,
>
> > > > I am new to this field. So, please pardon me if my questions are too
> > > > naive.
>
> > > >http://groups.google.com/group/hypertable-user/browse_thread/thread/a.
> > ..
>
> > > > tells us that Hypertable supports simple row/range level transactions.
>
> > > > My questions are:
>
> > > > 1. Is it like the traditional transaction support- i.e. including
> > > > locking, logging, recovery etc? If yes, where can I find related files
> > > > in the source?
> > > > 2. Is it similar/on the parallel lines of BigTable's tablet level
> > > > transaction support?
>
> > > > Thanks,
>
> > > > Harshada
>
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