Additionally if the time uuid is generated client side, make sure the boxes that will perform the write hava correct ntp/ptp configuration.
@John Haddad Keep in mind that in a distributed environment you probably have so much variance that nanosecond precision is pointless. Even google notes that in the paper, Dapper, a Large-Scale Distributed Systems Tracing Infrastructure [http://research.google.com/pubs/pub36356.html] I agree with your statement about variance. Though I just like to mention Dapper is about *tracing* query/code, more generally it’s about about the execution overhead of tracing, which is a bit different that just *timestamping*. -- Brice On Thu, Oct 29, 2015 at 2:45 PM, Clint Martin < clintlmar...@coolfiretechnologies.com> wrote: > Generating the time uuid on the server side via the now() function also > makes the operation non idempotent. This may not be a huge problem for your > application but it is something to keep in mind. > > Clint > On Oct 29, 2015 9:01 AM, "Kai Wang" <dep...@gmail.com> wrote: > >> If you want the timestamp to be generated on the C* side, you need to >> sync clocks among nodes to the nanosecond precision first. That alone might >> be hard or impossible already. I think the safe bet is to generate the >> timestamp on the client side. But depending on your data volume, if data >> comes from multiple clients you still need to sync clocks among them. >> >> >> On Thu, Oct 29, 2015 at 7:57 AM, <chandrasekar....@wipro.com> wrote: >> >>> Hi Doan, >>> >>> >>> >>> Is the timeBased() method available in Java driver similar to now() function >>> in cqlsh. Does both provide identical results. >>> >>> >>> >>> Also, the preference is to generate values during record insertion from >>> database side, rather than client side. Something similar to SYSTIMESTAMP >>> in Oracle. >>> >>> >>> >>> Regards, Chandra Sekar KR >>> >>> *From:* DuyHai Doan [mailto:doanduy...@gmail.com] >>> *Sent:* 29/10/2015 5:13 PM >>> *To:* user@cassandra.apache.org >>> *Subject:* Re: Oracle TIMESTAMP(9) equivalent in Cassandra >>> >>> >>> >>> You can use TimeUUID data type and provide the value yourself from >>> client side. >>> >>> >>> >>> The Java driver offers an utility class >>> com.datastax.driver.core.utils.UUIDs and the method timeBased() to generate >>> the TimeUUID. >>> >>> >>> >>> The precision is only guaranteed up to 100 nano seconds. So you can >>> have possibly 10k distincts values for 1 millsec. For your requirement of >>> 20k per sec, it should be enough. >>> >>> >>> >>> On Thu, Oct 29, 2015 at 12:10 PM, <chandrasekar....@wipro.com> wrote: >>> >>> Hi, >>> >>> >>> >>> Oracle Timestamp data type supports fractional seconds (upto 9 digits, 6 >>> is default). What is the Cassandra equivalent data type for Oracle >>> TimeStamp nanosecond precision. >>> >>> >>> >>> This is required for determining the order of insertion of record where >>> the number of records inserted per sec is close to 20K. Is TIMEUUID an >>> alternate functionality which can determine the order of record insertion >>> in Cassandra ? >>> >>> >>> >>> Regards, Chandra Sekar KR >>> >>> The information contained in this electronic message and any attachments >>> to this message are intended for the exclusive use of the addressee(s) and >>> may contain proprietary, confidential or privileged information. If you are >>> not the intended recipient, you should not disseminate, distribute or copy >>> this e-mail. Please notify the sender immediately and destroy all copies of >>> this message and any attachments. WARNING: Computer viruses can be >>> transmitted via email. The recipient should check this email and any >>> attachments for the presence of viruses. The company accepts no liability >>> for any damage caused by any virus transmitted by this email. >>> www.wipro.com >>> >>> >>> The information contained in this electronic message and any attachments >>> to this message are intended for the exclusive use of the addressee(s) and >>> may contain proprietary, confidential or privileged information. If you are >>> not the intended recipient, you should not disseminate, distribute or copy >>> this e-mail. Please notify the sender immediately and destroy all copies of >>> this message and any attachments. WARNING: Computer viruses can be >>> transmitted via email. The recipient should check this email and any >>> attachments for the presence of viruses. The company accepts no liability >>> for any damage caused by any virus transmitted by this email. >>> www.wipro.com >>> >> >>
