Timestamps can come from three different places, in order of precedence from highest to lowest: * The CQL query itself through the "USING TIMESTAMP" clause * The driver (or maybe application) at the protocol level when using the v3 native protocol or higher (which is available in Cassandra 2.1+). This is what I recommend using in most cases, because the driver can safely retry idempotent writes. * The coordinator node
On Fri, Sep 4, 2015 at 1:06 PM, Andrey Ilinykh <ailin...@gmail.com> wrote: > I meant thrift based api. If we are talking about CQL then timestamps are > generated by node you are connected to. This is a "client". > > On Fri, Sep 4, 2015 at 10:49 AM, ibrahim El-sanosi < > ibrahimsaba...@gmail.com> wrote: > >> Hi Andrey, >> >> I just came across this articale " >> >> "Each cell in a CQL table has a corresponding timestamp >> which is taken from the clock on *the Cassandra node* *that orchestrates the >> write.* When you are reading from a Cassandra cluster the node that >> coordinates the read will compare the timestamps of the values it fetches. >> Last write(=highest timestamp) wins and will be returned to the client." >> >> What do you think? >> >> " >> >> On Fri, Sep 4, 2015 at 6:41 PM, Andrey Ilinykh <ailin...@gmail.com> >> wrote: >> >>> Coordinator doesn't generate timestamp, it is generated by client. >>> >>> On Fri, Sep 4, 2015 at 10:37 AM, ibrahim El-sanosi < >>> ibrahimsaba...@gmail.com> wrote: >>> >>>> Ok, why coordinator does generate timesamp, as the write is a part of >>>> Cassandra process after client submit the request to Cassandra? >>>> >>>> On Fri, Sep 4, 2015 at 6:29 PM, Andrey Ilinykh <ailin...@gmail.com> >>>> wrote: >>>> >>>>> Your application. >>>>> >>>>> On Fri, Sep 4, 2015 at 10:26 AM, ibrahim El-sanosi < >>>>> ibrahimsaba...@gmail.com> wrote: >>>>> >>>>>> Dear folks, >>>>>> >>>>>> When we hear about the notion of Last-Write-Wins in Cassandra >>>>>> according to timestamp, *who does generate this timestamp during the >>>>>> write, coordinator or each individual replica in which the write is going >>>>>> to be stored?* >>>>>> >>>>>> >>>>>> *Regards,* >>>>>> >>>>>> >>>>>> >>>>>> *Ibrahim* >>>>>> >>>>> >>>>> >>>> >>> >> > -- Tyler Hobbs DataStax <http://datastax.com/>
