Yes, your scenario can occur, and will occur if your clocks are not sync’d.
Either you sync your clocks to appropriate tolerances, or you don’t write
without checking the existing value (with LWT). There is no other resolution in
cassandra – there are no vector clocks to allow you to manage the
Denormalize your data to support the query, e.g.:
CREATE TABLE name_by_cust_id (cust_id int, name text, PRIMARY KEY
> (cust_id));
> SELECT name WHERE cust_id = 3;
For additional queries, similarly denormalize.
Refer to https://academy.datastax.com/courses for free online courses
covering this t
Sent from Samsung Mobile.
Hi All,
I am trying to model RDBMS joins into cassandra. As I am new to cassandra, I
need your help/suggestion on this. Below is the information regarding the
query:
I have a query in RDBMS as follows:
select t3.name from Table1 t1, Table2 t2, Table3 t3, Ta
Yes, LWT is another case and different compared to what my scenario is
about. I am not talking about LWT and CAS, it is true that LWT uses logical
clock by utilising Paxos. But my scenario is talking about using timestamp
and Last-Write-Wins.
If anyone can read the above scenario and confirm w
In the cases where NTP and client timestamps with microsecond resolution is
insufficient, LWT “IF EXISTS, IF NOT EXISTS” is generally used.
From: ibrahim El-sanosi
Reply-To: "user@cassandra.apache.org"
Date: Sunday, September 6, 2015 at 7:40 AM
To: "user@cassandra.apache.org"
Subject: Re:
I have done some research about “timestamps could jump back and forth
arbitrarily if you talk to different nodes”.
To summarise, it is possible in Cassandra for following scenario can
happen in sequence:
1. Process A writes w1 with timestamp t=2
2. Process B reads w1
3. Process B writ
@ibrahim: When saying "clocks should be synchronized", it includes Cassandra
nodes AND clients
NTP is the way to go
Le 6 sept. 2015 à 14:56, Laing, Michael
mailto:michael.la...@nytimes.com>> a écrit :
https://en.wikipedia.org/wiki/Network_Time_Protocol
On Sun, Sep 6, 2015 at 8:23 AM, ibrahim
https://en.wikipedia.org/wiki/Network_Time_Protocol
On Sun, Sep 6, 2015 at 8:23 AM, ibrahim El-sanosi
wrote:
> Assume the Cassandra cluster is located in somewhere in US. Clients that
> connect from different part of the world will have different timestamp (if
> we rely on client timestamp to st
On Fri, Sep 4, 2015 at 3:50 PM, Marcus Olsson
wrote:
> Hi,
>
> While checking the repair documentation at
> http://docs.datastax.com/en/cassandra/2.1/cassandra/tools/toolsRepair.html
> I noticed the line *Use the **-hosts** option to list the good nodes to
> use for repairing the bad nodes. Use *
Assume the Cassandra cluster is located in somewhere in US. Clients that
connect from different part of the world will have different timestamp (if
we rely on client timestamp to store write) or If a coordinator is
responsible for generating timestamp during the write, it also may have
different ti
Cassandra is not changing clock settings; it does use it to omit TTL'ed rows in
compaction phases. So make sure your nodes agree on the very same time using
e.g. NTP. It is very crucial for data integrity on most distributed systems.
Date: Sun, 6 Sep 2015 13:10:14 +0100
Subject: Re: Is Cassandra
Do you mean Cassandra does synchronize the clock across all the cluster, if
yes how it does so, or could you refer me to any related article?
Thank you
Ibrahim
On Sun, Sep 6, 2015 at 1:00 PM, Laing, Michael
wrote:
> I think I saw this before.
>
> Clocks must be synchronized.
>
> On Sun, Sep 6
Yes, it can occur, if you allow it to occur.
Clients should send their own timestamps. Clocks should be synchronized.
Failure to do so while relying on ‘last write wins’ timestamp resolution will
cause undesirable results.
This is unrelated to strong/weak/eventual consistency discussions or
I think I saw this before.
Clocks must be synchronized.
On Sun, Sep 6, 2015 at 7:28 AM, ibrahim El-sanosi
wrote:
> Hi folks,
>
> Assume we have 4-nodes cluster N1, N2, N3, and N4 and replication factor
> is 3. When write CL =ALL and read CL=ONE:
>
> Client c1 sends W1 = [k1,V1] to N1 (a coordi
Hi folks,
Assume we have 4-nodes cluster N1, N2, N3, and N4 and replication factor is
3. When write CL =ALL and read CL=ONE:
Client c1 sends W1 = [k1,V1] to N1 (a coordinator). A coordinator (N1)
generates timestamp Mon 05-09-2015 11:30:40,200 (according to its local
clock) and assigned it to W
Hello everyone,
I'm new to this mailing list, and still fairly new to Cassandra. I'm a
systems administrator and have had a 3-node Cassandra cluster with a
replication factor of 3 running in Production for about a year now. We
have about 200 GB of data per node currently.
Up until recently I ha
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