On Tue, Aug 30, 2011 at 1:41 PM, Jeremy Hanna <jeremy.hanna1...@gmail.com>wrote:
> I would not use nano time with cassandra. Internally and throughout the > clients, milliseconds is pretty much a standard. You can get into trouble > because when comparing nanoseconds with milliseconds as long numbers, > nanoseconds will always win. That bit us a while back when we deleted > something and it couldn't come back because we deleted it with nanoseconds > as the timestamp value. > > See the caveats for System.nanoTime() for why milliseconds is a standard: > > http://download.oracle.com/javase/6/docs/api/java/lang/System.html#nanoTime%28%29 > > On Aug 30, 2011, at 12:31 PM, Jiang Chen wrote: > > > Looks like the theory is correct for the java case at least. > > > > The default timestamp precision of Pelops is millisecond. Hence the > > problem as explained by Peter. Once I supplied timestamps precise to > > microsecond (using System.nanoTime()), the problem went away. > > > > I previously stated that sleeping for a few milliseconds didn't help. > > It was actually because of the precision of Java Thread.sleep(). > > Sleeping for less than 15ms often doesn't sleep at all. > > > > Haven't checked the Python side to see if it's similar situation. > > > > Cheers. > > > > Jiang > > > > On Tue, Aug 30, 2011 at 9:57 AM, Jiang Chen <jia...@gmail.com> wrote: > >> It's a single node. Thanks for the theory. I suspect part of it may > >> still be right. Will dig more. > >> > >> On Tue, Aug 30, 2011 at 9:50 AM, Peter Schuller > >> <peter.schul...@infidyne.com> wrote: > >>>> The problem still happens with very high probability even when it > >>>> pauses for 5 milliseconds at every loop. If Pycassa uses microseconds > >>>> it can't be the cause. Also I have the same problem with a Java client > >>>> using Pelops. > >>> > >>> You connect to localhost, but is that a single node or part of a > >>> cluster with RF > 1? If the latter, you need to use QUORUM consistency > >>> level to ensure that a read sees your write. > >>> > >>> If it's a single node and not a pycassa / client issue, I don't know > off hand. > >>> > >>> -- > >>> / Peter Schuller (@scode on twitter) > >>> > >> > > Isn't the standard microseconds ? (System.currentTimeMillis()*1000L) http://wiki.apache.org/cassandra/DataModel The CLI uses microseconds. If your code and the CLI are doing different things with time BadThingsWillHappen TM
