For tracking delay in very recent versions, this exists: https://issues.apache.org/jira/browse/CASSANDRA-13289
-- Jeff Jirsa > On Jul 11, 2018, at 1:05 AM, Simon Fontana Oscarsson > <simon.fontana.oscars...@ericsson.com> wrote: > > I thought you just wanted to test how big delay you have, that's why I > suggested trace. > > Your best option is to write with EACH_QUORUM as Alain said. > That way you will get a response when the write is successful on all dcs. > The downside is that the request will fail if one dc is down. > As usual it's up to you to decide if that's acceptable or not. > You could follow up with a LOCAL_QUORUM request if the EACH_QUORUM fails and > rely on hints and repair to get consistency eventually. > > -- > SIMON FONTANA OSCARSSON > Software Developer > > Ericsson > Ölandsgatan 1 > 37133 Karlskrona, Sweden > simon.fontana.oscars...@ericsson.com > www.ericsson.com > >> On tis, 2018-07-10 at 16:32 +0000, Saladi Naidu wrote: >> Simon, >> Trace would be significant burden on the cluster and it has to be on all the >> time. I am trying to find a way to know when a row is written on demand >> basis, is there a way to determine that? >> >> Naidu Saladi >> >> >> On Tuesday, July 10, 2018 2:24 AM, Simon Fontana Oscarsson >> <simon.fontana.oscars...@ericsson.com> wrote: >> >> >> Have you tried trace? >> -- >> SIMON FONTANA OSCARSSON >> Software Developer >> >> Ericsson >> Ölandsgatan 1 >> 37133 Karlskrona, Sweden >> simon.fontana.oscars...@ericsson.com >> www.ericsson.com >> >>> On mån, 2018-07-09 at 19:30 +0000, Saladi Naidu wrote: >>> Cassandra is an eventual consistent DB, how to find when a row is actually >>> written in multi DC environment? Here is the problem I am trying to solve >>> >>> - I have multi DC (3 DC's) Cassandra cluster/ring - One of the application >>> wrote a row to DC1(using Local Quorum) and within span of 50 ms, it tried >>> to read same row from DC2 and could not find >> the >>> row. Our both DC's have sub milli second latency at network level, usually >>> <2 ms. We promised 20 ms consistency. In this case Application could not >>> find the row in DC2 in 50 ms >>> >>> I tried to use "select WRITETIME(authorizations_json) from >>> token_authorizations where ...." to find when the Row is written in each >>> DC, but both DC's returned same Timestamp. After further >> research >>> I found that Client V3 onwards Timestamp is supplied at Client level so >>> WRITETIME does not help >>> "https://docs.datastax.com/en/developer/java-driver/3.4/manual/query_timestamps/"; >>> >>> So how to determine when the row is actually written in each DC? >>> >>> >>> Naidu Saladi >>
