Re: Cassandra read throughput with little/no caching.

On 31/12/12 18:45, Tyler Hobbs wrote: On Mon, Dec 31, 2012 at 11:24 AM, James Masson mailto:james.mas...@opigram.com>> wrote: Well, it turns out the Read-Request Latency graph in Ops-Center is highly misleading. Using jconsole, the read-latency for the column family in question

Inter-Cluster Communication

Hi people, I would to know if it is possible to create 2 clusters, in the first constain just meta-data and in the second just the real data. How the system will comunicate with this both cluster and one cluster communicate with other? Could any one help me? Thanks. -- Everton Lima Aleixo Bacha

Re: Question on TTLs and Tombstones

Yup, I know it was pretty long mail and it was Christmas time, so I thought it might be left without a reply for some time, but as some time has passed, I'll try to remind you about my question with additional help: TL;DR version: WHEN does Cassandra remove expired (because of TTL) data? Which

Re: Question on TTLs and Tombstones

> WHEN does Cassandra remove expired (because of TTL) data? When a compaction reads an expired column, it removes it and replaces it by a tombstone (i.e. a deleted marker). So the first compaction after the expiration is what actually removes the data, but it won't reclaim all the disk space yet d

[RELEASE] Apache Cassandra 1.2 released

The Cassandra team wishes you a very happy new year 2013, and is very pleased to announce the release of Apache Cassandra version 1.2.0. Cassandra 1.2.0 is a new major release for the Apache Cassandra distributed database. This version adds numerous improvements[1,2] including (but not restricted t

Re: Question on TTLs and Tombstones

Thanks for your answer. Moreover, the issue you mentioned in the end was the answer to the question I was going to ask next ;-) Regards, Michał W dniu 02.01.2013 15:42, Sylvain Lebresne pisze: WHEN does Cassandra remove expired (because of TTL) data? When a compaction reads an expired column

Re: Cassadra API for Java

You can check the cassandra list of java clients http://wiki.apache.org/cassandra/ClientOptions From: Brian Tarbox mailto:tar...@cabotresearch.com>> Reply-To: "user@cassandra.apache.org" mailto:user@cassandra.apache.org>> Date: Sunday, December 30, 2012 11:03 AM

Re: Cassandra read throughput with little/no caching.

On Wed, Jan 2, 2013 at 5:28 AM, James Masson wrote: > > thanks for clarifying this. So you're saying the difference between the > global Read Request latency in opscenter, and the column family specific > one is in the effort coordinating a validated read across multiple replicas? Yes. > Is th

Re: Cassandra read throughput with little/no caching.

On 02/01/13 16:18, Tyler Hobbs wrote: On Wed, Jan 2, 2013 at 5:28 AM, James Masson mailto:james.mas...@opigram.com>> wrote: > 1) Hector sends a request to some node in the cluster, which will act as the coordinator. 2) The coordinator then sends the actual read requests out to each of the (RF

Re: Inter-Cluster Communication

On Wed, Jan 2, 2013 at 4:33 AM, Everton Lima wrote: > I would to know if it is possible to create 2 clusters, in the first > constain just meta-data and in the second just the real data. How the system > will comunicate with this both cluster and one cluster communicate with > other? Could any one

Force data to a specific node

It is possible to force a data to stay in a specific node? -- Everton Lima Aleixo Bacharel em Ciência da Computação pela UFG Mestrando em Ciência da Computação pela UFG Programador no LUPA

Re: Inter-Cluster Communication

Ok. Thanks. 2013/1/2 Rob Coli > On Wed, Jan 2, 2013 at 4:33 AM, Everton Lima > wrote: > > I would to know if it is possible to create 2 clusters, in the first > > constain just meta-data and in the second just the real data. How the > system > > will comunicate with this both cluster and one cl

Re: Force data to a specific node

Why would you want to? From: Everton Lima To: Cassandra-User Sent: Wed Jan 02 18:03:49 2013 Subject: Force data to a specific node It is possible to force a data to stay in a specific node? -- Everton Lima Aleixo Bacharel em Ciência da Computação pela UFG Mestr

Re: Force data to a specific node

We need to do this to minimize the network I/O. We have our own load data balance algorithm. We have some data that is best to process in a local machine. Is it possible? How? 2013/1/2 Edward Sargisson > Why would you want to? > > -- > *From*: Everton Lima > *To*: C

How to show unread messages counts?

Happy New Year Everyone! What's the best way to model "unread messages count" in Cassandra? I have a UserMessage CF where the row key is the user id and the column name is the message id (timeuuid) and I store the message and the status (READ/UNREAD) in the value column. I would like to be able

Re: Force data to a specific node

You'd have to use the ordered partitioner or something like that and choose your row key according to the node you want it placed. But that's in general a really bad idea because you end up with unbalanced nodes and hot spots. That said, are your nodes on a LAN? I have my 9+3 node cluster (two d

Re: Force data to a specific node

There is a crazy, very bad, don't do it way to do this. You can set RF=1 and hack the "LocalPartitioner" (because the local partitioner has been made not to do this) Then the node you connect to and write is the node the data will get stored on. Its like memcache "do it yourself" style sharding.

Re: How to show unread messages counts?

> Currently I'm thinking of having a separate Counter CF just to keep the > number of unread messages in there. Is this a good approach? Yup. Add a UserMetrics CF with columns for the counts you want to keep. Cheers - Aaron Morton Freelance Cassandra Developer New Zealand @aar

Re: How to show unread messages counts?

Thanks Aaron. On Jan 2, 2013, at 2:55 PM, aaron morton wrote: >> Currently I'm thinking of having a separate Counter CF just to keep the >> number of unread messages in there. Is this a good approach? > Yup. > Add a UserMetrics CF with columns for the counts you want to keep. > > Cheers > >

Re: Column Family migration/tombstones

> 1) As one can imagine, the index and bloom filter for this column family is > large. Am I correct to assume that bloom filter and index space will not be > reduced until after gc_grace_period? Yes. > 2) If I would manually run repair across a cluster, is there a process I can > use to safel