Re: Multi-type column values in single CF

We do pretty much the same thing here, dynamic column with a timestamp for column name and a different value type for each row. We use the serialization/deserialization classes provided with Hector and store the type of the value in the key of the row. Example of row key: "b6c8a1e7281761e62230ea76d

Re: Multi-type column values in single CF

I appreciate both your answers. I'll use them soon. Thanks! On Mon, Jul 4, 2011 at 11:48 AM, Silvère Lestang wrote: > We do pretty much the same thing here, dynamic column with a timestamp for > column name and a different value type for each row. We use the > serialization/deserialization class

Re: Row cache

Hi, The row cache capacity > 0. after reading a row - the Caches..KeyCache.Requests attribute gets incremented but the ColumnFamilies...ReadCount attribute remains zero and the Caches..RowCache.Size and Requsts attributes remain zero as well. It looks like the row-cache is disabled although the

How to scale Cassandra?

Hi there, I read a lot of Cassandra's high scalability feature: allowing seamless addition of nodes, no downtime etc. But I wonder how one will do this in practice in an operational system. In the system we're going to implement we're expecting a huge number of writes with uniformly distribut

Re: How to scale Cassandra?

That's basically how I understand it. However, I think it gets better with larger clusters as the proportion of the ring you move around at any time is much lower. On Mon, Jul 4, 2011 at 10:54 AM, Subscriber wrote: > Hi there, > > I read a lot of Cassandra's high scalability feature: allowing s

flushing issue

Hi, I know, I might be missing something here. I am currently facing 1 issue. I have 2 cassandra clients(1. Using CassandraServer 2. Using Cassandra.Client) running connecting to same host. I have created Keyspace K1, K2 using client1(e.g. CassandraServer), but somehow those keyspaces are not a

Cassandra memory problem

Hi all, we have a mem problem with cassandra. res goes up without bounds (well until the os kills the process because we dont have swap) I found a thread that's about the same problem but on OpenJDK: http://cassandra-user-incubator-apache-org.3065146.n2.nabble.com/Very-high-memory-utilization-n

Re: Row cache

Just to make sure: The yaml doesn't matter. The cache config is stored in the system tables. Its the "CREATE ... WITH ..." stuff you did via cassandra-cli to create the CF. In Jconsole you see that the cache capacity is > 0? On Jul 4, 2011, at 11:18 AM, Shay Assulin wrote: > Hi, > > The row c

Re: Cassandra memory problem

mmap'd data will be attributed to res, but the OS can page it out instead of killing the process. On Mon, Jul 4, 2011 at 5:52 AM, Daniel Doubleday wrote: > Hi all, > we have a mem problem with cassandra. res goes up without bounds (well until > the os kills the process because we dont have swap)

Re: Cassandra memory problem

We had an issue like that a short while ago here. This was mainly happening under heavy load and we managed to stabilize it by tweaking the Young/Old space ratio of the JVM and by also tweaking the tenuring thresholds/survivor ratios. What kind of load to you have on your systems? Mostly reads, wri

RE: How to scale Cassandra?

Moving nodes does not result in downtime provide you use proper replication factors and read/write consistencies. The typical recommendation is RF=3 and QUORUM reads/writes. Dan From: Paul Loy [mailto:ketera...@gmail.com] Sent: July-04-11 5:59 To: user@cassandra.apache.org Subject: Re: How

Re: How to scale Cassandra?

Well, by issuing a nodetool move when a node is under high load, you basically make that node unresponsive. That's fine, but a nodetool move on one node also means that that node's replica data needs to move around the ring and possibly some replica data from the next (or previous) node in the ring

Re: Cassandra memory problem

Just to make sure: You were seeing that res mem was more than twice of max java heap and that did change after you tweaked GC settings? Note that I am not having a heap / gc problem. The VM itself thinks everything is golden. On Jul 4, 2011, at 3:41 PM, Sebastien Coutu wrote: > We had an issu

copy data from multi-node cluster to single node

Hi, I am using Cassandra 0.7.5 on Linux machines. I am trying to backup data from a multi-node cluster (3 nodes) and restore it into a single node cluster that has a different name (for development testing). The multi-node cluster is backed up using clustertool global_snapshot, and then I copy t

Re: How to scale Cassandra?

On Mon, Jul 4, 2011 at 10:21 AM, Paul Loy wrote: > Well, by issuing a nodetool move when a node is under high load, you > basically make that node unresponsive. That's fine, but a nodetool move on > one node also means that that node's replica data needs to move around the > ring and possibly som

Re: Cassandra memory problem

It was among one of the issues we had. One of our hosts was using OpenJDK and we've switched it to Sun and this part of the issue stabilized. The other issues we had were Heap going through the roof and then OOM under load. On Mon, Jul 4, 2011 at 11:01 AM, Daniel Doubleday wrote: > Just to make

Re: Cassandra memory problem

Yes thank you. I have read about the OpenJDK issue but unfortunately we are already on Sun JDK. On Jul 4, 2011, at 6:04 PM, Sebastien Coutu wrote: > It was among one of the issues we had. One of our hosts was using OpenJDK and > we've switched it to Sun and this part of the issue stabilized. T

Re: Cassandra memory problem

Ok - thanks but maybe some kernel guy can help or point to some good resource to get educated because I don'r really get it. The following is from our other small log cluster with 2 nodes with 8GM ram cassandra has 4GB max heap - We have disabled swap on all cassandra servers - On the machine w

Re: Cassandra memory problem

Hi Sebastian, one question: do you use jna.jar and do you see JNA mlockall successful in your logs. There's that wild theory here that our problem might be related to mlockall and no swap. Maybe the JVM does some realloc stuff and the pinned pages are not cleared ... but that's really only wi

Re: How to scale Cassandra?

Do you mean the ring does not change until the move has completed? On Mon, Jul 4, 2011 at 4:49 PM, Edward Capriolo wrote: > > > On Mon, Jul 4, 2011 at 10:21 AM, Paul Loy wrote: > >> Well, by issuing a nodetool move when a node is under high load, you >> basically make that node unresponsive. Tha

Re: Cassandra memory problem

Hi Daniel, Yes we do see it, since I've added the JNA libraries, it takes a bit more time at that step and locks all the memory. We're using JNA 3.3.0 we've downloaded from there: https://github.com/twall/jna#readme Our servers currently have 32GB of memory a

Re: How to scale Cassandra?

Let's assume you have 50 nodes and their work-load grows simultaneously. You discover that the nodes are about to reach their limits (btw. what is the actual limit of a Cassandra node? 100GB? 500GB? 1TB?) You decide to add another 50 nodes. Do you do this within one step? Or one after the other

Re: How to scale Cassandra?

Hi Udo, I didn't read the whole thread but can you define the type of workload you're looking at? Do you have jobs that require reading the whole data stored in your database? For example one big column family that needs to be read entirely by a job? Because the amount of time required to read a w

Re: How to scale Cassandra?

Hi SC, I'm just talking about workload in general. The point is that sooner or later you come to the point that you need to scale-out. And the question is, what's the best strategy here? Especially when your cluster is almost balanced. 500 GB seems to be a good ball-park figure, I think I read

RowKey in hexadecimal in CLI

Hello! Since we installed cassandra 0.8, the RowKeys are displayed in hexadecimal in the CLI. Any idea why and how to fix that? Thanks in advance Sebastien

Re: RowKey in hexadecimal in CLI

Because you haven't declared a key_validation_class. On Mon, Jul 4, 2011 at 4:19 PM, Sébastien Druon wrote: > Hello! > Since we installed cassandra 0.8, the RowKeys are displayed in hexadecimal > in the CLI. > Any idea why and how to fix that? > Thanks in advance > Sebastien -- Jonathan Ellis

Re: secondary index performance

> Is the assumption that rows/keys cached is inherited correct? Is there any > way to see cfstats on secondary index sub-column families? They are inherited, but AFAIK only at the time the secondary index is created. You would need to drop and re-create the secondary index to see it change. c

Re: flushing issue

When you say using CassandraServer do you mean an embedded cassandra server ? What process did you use to add the Keyspaces ? Adding a KS via the thrift API should take care of everything. The simple test is stop the server and the clients, start the server again and see if the KS is defined by

Re: copy data from multi-node cluster to single node

> How do you change the name of a cluster? The FAQ instructions do not seem to > work for me - are they still valid for 0.7.5? > Is the backup / restore mechanism going to work, or is there a better/simpler > to copy data from multi-node to single-node? Bug fixed on 0.7.6 https://github.com/ap

Re: copy data from multi-node cluster to single node

On Tue, Jul 5, 2011 at 8:58 AM, aaron morton wrote: > How do you change the name of a cluster? The FAQ instructions do not seem > to work for me - are they still valid for 0.7.5? > Is the backup / restore mechanism going to work, or is there a > better/simpler to copy data from multi-node to sing

connection issue

Hi, When I am using multithreading with Cassandra Query Language ,I have to make connections for each thread. A single connection object for whole of the thread pool is not working. I am using JDBC for connectivity. I know ,I may be missing something. Any help/suggestions? ___

RE: RowKey in hexadecimal in CLI

As of Cassandra 0.8, we need to declare a key_validataion_class for the column family: For example: update column family User with key_validation_class=UTF8Type; From: Sébastien Druon [mailto:sdr...@spotuse.com] Sent: 05 July 2011 02:50 To: user@cassandra.apache.org Subject: RowKey in hexadecim