I think this request belongs in the java driver jira not the Cassandra jira.
https://datastax-oss.atlassian.net/projects/JAVA/ all the best, Sebastián On May 10, 2016 1:09 AM, "Lu, Boying" <boying...@emc.com> wrote: > I filed a JIRA https://issues.apache.org/jira/browse/CASSANDRA-11741 to > track this. > > > > *From:* DuyHai Doan [mailto:doanduy...@gmail.com] > *Sent:* 2016年5月10日 12:47 > *To:* user@cassandra.apache.org > *Subject:* Re: A question to 'paging' support in DataStax java driver > > > > I guess it's technically possible but then we'll need to update the binary > protocol. Just create a JIRA and ask for this feature > > > > On Tue, May 10, 2016 at 5:00 AM, Lu, Boying <boying...@emc.com> wrote: > > Thanks very much. > > > > I understand that the data needs to be read from the DB to get the next > ‘PagingState’. > > > > But is it possible not to return those data to the client side, just > returning the ‘PagingState’? > > I.e. the data is read on the server side, but not return to client side, > this can save some bandwidth > > between client and server. > > > > > > *From:* DuyHai Doan [mailto:doanduy...@gmail.com] > *Sent:* 2016年5月9日 21:06 > *To:* user@cassandra.apache.org > *Subject:* Re: A question to 'paging' support in DataStax java driver > > > > In a truly consistent world (should I say "snapshot isolation" world > instead), re-reading the same page should yield the same results no matter > how many new inserts have occurred since the last page read. > > > > Caching previous page at app level can be a solution but not viable if the > amount of data is huge, also you'll need a cache layer and deal with cache > invalidation etc ... > > > > The point is, providing snapshot isolation in a distributed system is hard > without some sort of synchronous coordination e.g. global lock (read > http://www.bailis.org/papers/hat-vldb2014.pdf) > > > > > > On Mon, May 9, 2016 at 2:17 PM, Bhuvan Rawal <bhu1ra...@gmail.com> wrote: > > Hi Doan, > > > > What does it have to do being eventual consistency? Lets assume a scenario > with complete consistency and we are at page X, and at the same time some > inserts/updates happened at page X-2 and we jumped to that. > > User will see inconsistent page in that case as well, right? Also in such > cases how would you design a user facing application (Cache previous pages > at app level?) > > > > Regards, > > Bhuvan > > > > On Mon, May 9, 2016 at 4:18 PM, DuyHai Doan <doanduy...@gmail.com> wrote: > > "Is it possible to just return PagingState object without returning > data?" --> No > > > > Simply because before reading the actual data for each page of N rows, you > cannot know at which token value a page of data starts... > > > > And it is worst than that, with paging you don't have any isolation. Let's > suppose you keep in your application/web front-end the paging states for > page 1, 2 and 3. Since there are concurrent inserts on the cluster at the > same time, when you re-use the paging state 2 for example, you may not get > the same results as the previous read. > > > > And it is inevitable in an eventual consistent distributed DB world > > > > On Mon, May 9, 2016 at 12:25 PM, Lu, Boying <boying...@emc.com> wrote: > > dHi, All, > > > > We are considering to use DataStax java driver in our codes. One important > feature provided by the driver we want to use is ‘paging’. > > But according to the > https://datastax.github.io/java-driver/3.0.0/manual/paging/, it seems > that we can’t jump between pages. > > > > Is it possible to just return PagingState object without returning data? > e.g. If I want to jump to the page 5 from the page 1, > > I need to go through each page from page 1 to page 5, Is it possible to > just return the PagingState object of page 1, 2, 3 and 4 without > > actual data of each page? This can save some bandwidth at least. > > > > Thanks in advance. > > > > Boying > > > > > > > > > > > > >
