Hi Nandan,
Take a look at the GossipingPropertyFileSnitch:
http://cassandra.apache.org/doc/latest/operating/snitch.html#snitch-classes
You'll also need to configure the cassandra-rackdc.properties file on each
node:
https://github.com/apache/cassandra/blob/trunk/conf/cassandra-rackdc.properties
Hello,
I am Seung-ho and I work as a Data Engineer in Korea. I need some advice.
My company recently consider replacing RDMBS-based system with Cassandra and
Hadoop.
The purpose of this system is to analyze Cadssandra and HDFS data with Spark.
It seems many user cases put emphasis on data local
Hi ,
Recently we are seeing huge batches and log prints as below in c* logs
*Batch of prepared statements for [ks1.cf1] is of size 413350, exceeding
specified threshold of 5120 by 362150*
Along with the Column Family name (as found in above log print) , we would
like to know the partion key , cl
If you use Containers like Docker Plan A can work provided you do the
resource and capacity planning. I tend to think that Plan B is more
Standard and easier Although you can wait to hear from others for a second
opinion.
Caution: Data Locality will make sense if the Disk throughput is
significant
Hi
Something to consider before moving to Apache Spark and Cassandra
I have a background where we have tons of data in Cassandra, and we wanted to
use Apache Spark to run various jobs
We loved what we could do with Spark, BUT….
We realized soon that we wanted to run multiple jobs in parallel
Some
Interesting
Tobias, when you said "Instead we transferred the data to Apache Kudu", did
you transfer all Cassandra data into Kudu from with a single migration and
then tap into Kudo for aggregation or did you run data import every
day/week/month from Cassandra into Kudu ?
>From my point of view,
Hi
What I wanted was a dashboard with graphs/diagrams and it should not take
minutes for the page to load
Thus, it was a problem to have Spark with Cassandra, and not solving the
parallelization to such an extent that I could have the diagrams rendered in
seconds.
Now with Kudu we get some decen
Did you make sure auto_bootstrap property is indeed set to [true] when you
added the node?
From: Junaid Nasir [mailto:jna...@an10.io]
Sent: Monday, June 05, 2017 6:29 AM
To: Akhil Mehra
Cc: Vladimir Yudovin ; user@cassandra.apache.org
Subject: Re: Convert single node C* to cluster (rebalancing p
Please share exact timeout error message text to get idea what type of timeout
you're facing.
From: Nitan Kainth [mailto:ni...@bamlabs.com]
Sent: Wednesday, June 07, 2017 7:24 AM
To: vasu gunja
Cc: user@cassandra.apache.org
Subject: Re: Local_serial >> Adding nodes
What is in system log?
Does
Check status of load with nodetool status command. Make sure your there isn’t
huge number of pending compactions for your tables. Ideally speaking data
distribution should be even across your nodes.
you should have reserved extra 15% of free space relative to your maximum size
of your table i.e
I don't believe the keys within a large batch are logged by Cassandra. A
large batch could potentially contain tens of thousands of primary keys, so
this could quickly fill up the logs.
Here are a couple of suggestions:
- Large batches should also be slow, so you could try setting up slow
q
Hi,
I am working on Music database where we have multiple order of users of our
portal. Different category of users is having some common attributes but
some different attributes based on their registration.
This becomes a hierarchy pattern. I am attaching one sample hierarchy
pattern of User Modu
Hello there,
We have some use cases are doing consistent read/write requests, and we
have 4 replicas in that cluster, according to our setup.
What's interesting to me is that, for both read and write quorum requests,
they are blocked for 4/2+1 = 3 replicas, so we are accessing 3 (for write)
+ 3 (
2/4 for write and 2/4 for read would not be sufficient to achieve strong
consistency, as there is no overlap.
In your particular case you could potentially use QUORUM for write and TWO
for read (or vice-versa) and still achieve strong consistency. If you add
additional nodes in the future this wou
Justin, what I suggest is that for QUORUM consistent level, the block for
write should be (num_replica/2)+1, this is same as today, but for read
request, we just need to access (num_replica/2) nodes, which should provide
enough strong consistency.
Dikang.
On Thu, Jun 8, 2017 at 7:38 PM, Justin Ca
It would be a little weird to change the definition of QUORUM, which means
majority, to mean something other than majority for a single use case.
Sounds like you want to introduce a new CL, HALF.
On Thu, Jun 8, 2017 at 7:43 PM Dikang Gu wrote:
> Justin, what I suggest is that for QUORUM consisten
So, for the quorum, what we really want is that there is one overlap among
the nodes in write path and read path. It actually was my assumption for a
long time that we need (N/2 + 1) for write and just need (N/2) for read,
because it's enough to provide the strong consistency.
On Thu, Jun 8, 2017
> So, for the quorum, what we really want is that there is one overlap among
> the nodes in write path and read path. It actually was my assumption for a
> long time that we need (N/2 + 1) for write and just need (N/2) for read,
> because it's enough to provide the strong consistency.
>
You are wr
>
>
> So, for the quorum, what we really want is that there is one overlap among
>> the nodes in write path and read path. It actually was my assumption for a
>> long time that we need (N/2 + 1) for write and just need (N/2) for read,
>> because it's enough to provide the strong consistency.
>>
>
>
We have CL.TWO.
On Thu, Jun 8, 2017 at 10:03 PM, Dikang Gu wrote:
> So, for the quorum, what we really want is that there is one overlap among
> the nodes in write path and read path. It actually was my assumption for a
> long time that we need (N/2 + 1) for write and just need (N/2) for read,
>
> We have CL.TWO.
>
>
>
This was actually the original motivation for CL.TWO and CL.THREE if memory
serves:
https://issues.apache.org/jira/browse/CASSANDRA-2013
To me, CL.TWO and CL.THREE are more like work around of the problem, for
example, they do not work if the number of replicas go to 8, which does
possible in our environment (2 replicas in each of 4 DCs).
What people want from quorum is strong consistency guarantee, as long as
R+W > N, there are th
I don't disagree with you there and have never liked TWO/THREE. This is
somewhat relevant: https://issues.apache.org/jira/browse/CASSANDRA-2338
I don't think going to CL.FOUR, etc, is a good long-term solution, but I'm
also not sure what is.
On Thu, Jun 8, 2017 at 11:20 PM, Dikang Gu wrote:
>
Would love to see real pluggable consistency levels. Sorta sad it got
wont-fixed - may be time to revisit that, perhaps it's more feasible now.
https://issues.apache.org/jira/browse/CASSANDRA-8119 is also semi-related,
but a different approach (CL-as-UDF)
On Thu, Jun 8, 2017 at 9:26 PM, Brandon W
Firstly, this situation only occurs if you need strong consistency and are
using an even replication factor (RF4, RF6, etc).
Secondly, either the read or write still need to be performed at a minimum
level of QUORUM. This means there are no extra availability benefits from
your proposal (i.e. a min
Short of actually making ConsistencyLevel pluggable or adding/changing one
of the existing levels, an alternative approach would be to divide up the
cluster into either real or pseudo-datacenters (with RF=2 in each DC), and
then write with QUORUM (which would be 3 nodes, across any combination of
d
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