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From Jonathan Haddad <...@jonhaddad.com>
Subject Re: Read after Write inconsistent at times
Date Fri, 24 Feb 2017 17:42:15 GMT
WRT to NTP, I first encountered this issue on my first cluster.  The
problem with ntp isn't just if you're doing inserts, it's if you're doing
inserts in combination with deletes, and using server timestamps with a
greater variance than the period between the delete and the insert.
Basically, you end up with a delete in the future and an insert in the
past, and the delete timestamp > insert timestamp.

+1 to Jan's recommendation on checking for dropped messages.


On Fri, Feb 24, 2017 at 9:35 AM Petrus Gomes <petrusgf@gmail.com> wrote:

> Hi,
>
> Check the tombstone count, If is it to high, your query will be impacted.
>
> If tombstone is a problem, you can try to reduce your "gc_grace_seconds"
> to reduce tombstone count(Carefully because you use cross data centers).
>
> Tchau,
> Petrus Silva
>
>
>
> On Fri, Feb 24, 2017 at 12:07 AM, Jan Kesten <j.kesten@enercast.de> wrote:
>
> Hi,
>
> are your nodes at high load? Are there any dropped messages (nodetool
> tpstats) on any node?
>
> Also have a look at your system clocks. C* needs them in thight sync - via
> ntp for example. Side hint: if you use ntp use the same set of upstreams on
> all of your nodes - ideal your own one. Using pool.ntp.org might lead to
> minimal dirfts in time across your cluster.
>
> Another thing that could help you out is using client side timestamps:
> https://docs.datastax.com/en/developer/java-driver/3.1/manual/query_timestamps/
> (of course only when you are using a single client or all clients are in
> sync via ntp).
>
>
>
> Am 24.02.2017 um 07:29 schrieb Charulata Sharma (charshar):
>
>
> Hi All,
>
> In my application sometimes I cannot read data that just got inserted.
> This happens very intermittently. Both write and read use LOCAL QUOROM.
>
> We have a cluster of 12 nodes which spans across 2 Data Centers and a RF
> of 3.
>
> Has anyone encountered this problem and if yes what steps have you taken
> to solve it
>
> Thanks,
> Charu
>
>
> --
> Jan Kesten, mailto:j.kesten@enercast.de
> Tel.: +49 561/4739664-0 FAX: -9 Mobil: +49 160 / 90 98 41 68
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