Bryan Duxbury 写道:
startUpdate is deprecated in TRUNK. Also, it doesn't do what you are
thinking it does. Committing a BatchUpdate is atomic across the whole
row, however. There is currently no way to make a get and a commit
transactional, though there is an issue open for
write-if-not-modified-since support. If this is something you need we
can talk about how it might be supported.
Thanks for answering my questions.
So currently HBase is not suitable for transactional web applications.
A simple counting transaction can not work by concurrent accesses:
transaction{
get(x);
x++;
write(x);
}
In my opinion, "write-if-not-modified-since" support may not be the best
idea of implement single-row transaction.
Because if write can not be performed, application has to try again and
again, or just return error and leave user to choose again or abort.
Probably locking, waiting and scheduling at region server might be
preferable in this case.
Is the single-row transaction feature currently in the roadmap of HBase?
Zhou
-Bryan
On May 7, 2008, at 7:48 PM, Zhou Wei wrote:
Hi
Does HBase support single-row transaction as described in Bigtable
paper?
"Bigtable supports single-row transactions, which can be
used to perform atomic read-modify-write sequences on
data stored under a single row key." --Bigtable paper
If so, how can I define a transaction in HBase,
is it looks like this:
lid=startUpdate
get(lid)
..
put(lid)
...
commit(lid)
Are these transactions isolated with each other?
If not, is there a way to achieve that?
Thanks
Zhou
