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  • Is sstable2json broken in Cassandra 0.6.0-beta3?

    - by knorv
    I'm getting NullPointerException:s when using sstable2json in Cassandra 0.6.0-beta3: $ bin/sstable2json .../cassandra/data/system/LocationInfo-1-Data.db Exception in thread "main" java.lang.NullPointerException at java.util.Arrays$ArrayList.<init>(Arrays.java:3357) at java.util.Arrays.asList(Arrays.java:3343) at org.apache.cassandra.tools.SSTableExport.export(SSTableExport.java:255) at org.apache.cassandra.tools.SSTableExport.export(SSTableExport.java:299) at org.apache.cassandra.tools.SSTableExport.export(SSTableExport.java:323) at org.apache.cassandra.tools.SSTableExport.main(SSTableExport.java:367) I've had no problems with sstable2json when using Cassandra 0.5. Is sstable2json broken in Cassandra 0.6.0-beta3 or am I doing something wrong?

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  • How to get a list of items when using cassandra

    - by Blankman
    When using a nosql type datastore like Cassandra, how would you return a result set based on a column? e.g. SELECT * FROM Articles WHERE category='blah' ORDER BY datetime DESC is this something that you would store in a sql db and then pull the data from cassandra? Or can cassandra handle this type of query? (assuming millions of rows in a db) From what I understand, cassandra is great at key based lookups, confused if it can and should be used for getting a list of data back and paging that data also (and if it is highly performant)

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  • The usage of Cassandra's internal keyspace "system"

    - by knorv
    The default Cassandra systems keyspace system is present in all Cassandra installations. Judging from the output of the describe keyspace command the keyspace it is used partly for "persistent metadata for the local node" (LocationInfo) and partly for "hinted handoff data". What persistent metadata for the local node is stored in system/LocationInfo? What is the definition of hinted handoff in Cassandra terminology? What hinted handoff data is stored in the system keyspace?

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  • Can sphinx be used over cassandra?

    - by Mickey Shine
    I am planning to build a cassandra store system and also I need a full-text(Chinese) system too. Can sphinx be used on cassandra? (sphinx supports xml format but I am not going to use it, cause it is slow and much of time are spent on xml parsing). Or you can share your experiences if you have ever built a full-text searching system over cassandra. Thank you

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  • MySQL app with Cassandra in mind

    - by SODA
    I am planning to make a web app which will eventually use Cassandra. But now that I don't have it and don't have server(s) to run it from, I'd like to start by using MySQL. The question is, is it possible to structure data and queries in such a way that it would be fairly easy to later port it to Cassandra? Main idea, I guess, would be writing MySQL queries that would be possible to change to same Cassandra queries. Maybe you have a better suggestion?

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  • Cassandra Production ready on Windows?

    - by BlackTea
    Question anyone know of any success stories of Cassandra running on windows in a production environment? I'm doing some work on Cassandra and trying to find the correct platform for it currently the platform is windows running MS-SQLas the data store. what are the dis-advantages if any when running Cassandra on a windows environment.

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  • Complex Quary on cassandra

    - by Sadiqur Rahman
    I have heard on cassandra database engine few days ago and searching for a good documentation on it. after studying on cassandra I got cassandra is more scalable than other data engine. I also read on Amazon SimpleDB but as SimpleDB has a limitation 10GB/table and Google Datastore is slower than Amazon SimpleDB, I prefer not to use them (Google Datastore, Amazon SimpleDB). So for making our site scaled specially high write rates with massive data, I like to use Cassandra as out Data Engine. But before starting using cassandra I am confused on "How to handle complex data using casssandra". I am giving you the MySQL database structure below, Please read this and give me a good suggestion. Users Table hasColum ID Primary hasColum email Unique hasColum FirstName hasColum LastName Category Table hasColum ID Primary hasColum Parent hasColum Category Posts Table hasColum ID Primary hasColum UID Index foreign key linked to users-ID hasColum CID Index foreign key linked to Category-ID hasColum Title hasColum Post Index hasColum PunDate Comments hasColum ID primary hasColum UID Index foreign key linked to users-ID hasColum PID Index foreign key linked to Posts-ID hasColum Comment User Group hasColum ID primary hasColum Name UserToGroup Table (for many to many relation only) hasColum UID foreign key linked to Users-ID hasColum GID foreign key linked to Group-ID Finally for your information, I like to use SimpleCassie PHP Class http://code.google.com/p/simpletools-php/ So, it will be very helpful if you can give me example using SimpleCassie

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  • Uneven Cassandra load

    - by David Keen
    Should a three node Cassandra cluster with a replication factor of 3 have the same load value for all three nodes? We are using a random partitioner and NetworkTopologyStrategy. Nodetool ring shows equal values for "Owns" but unequal values for "Load". Load Owns Token 113427455640312821154458202477256070484 16.53 GB 33.33% 0 14.8 GB 33.33% 56713727820156410577229101238628035242 15.65 GB 33.33% 113427455640312821154458202477256070484 Running nodetool repair and cleanup on each node brought the load a little closer but it still seems quite unbalanced. Is this considered normal?

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  • Dynamically changing one-node Cassandra cluster to two nodes

    - by Jason Axelson
    So I have an application that will be very dormant most of the time but will need high-bursting a few days out of the month. Since we are deploying on EC2 I would like to keep only one Cassandra server up most of the time and then on burst days I want to bring one more server up (with more RAM and CPU than the first) to help serve the load. What is the best way to do this? Should I take a different approach? Some notes about what I plan to do: Bring the node up and repair it immediately After the burst time is over decommission the powerful node Use the always-on server as the seed node My main question is how to get the nodes to share all the data since I want a replication factor of 2 (so both nodes have all the data) but that won't work while there is only one server. Should I bring up 2 extra servers instead of just one?

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  • How do I test is storage-conf is being loaded in Cassandra 0.7.3?

    - by user657253
    I have installed Cassandra and gotten it working on two machines. I have followed the instructions to hook them up to each other by configuring the storage-conf.xml files. Both machines respond well to thrift and to command line cassandra. This is tutorial I used to setup the storage-conf.xml files. The tutorial says that if I run netstat, I should NOT see Cassandra bound to 127.0.0.1 on my seed node. I should see it bound to my internal IP, which I have configured in the storage-conf.xml file. I have rebooted the servers and relaunched cassandra. Still, I see the localhost address insead of the correct internal IP address. Is it that my .yaml file is overriding the storage-conf.xml file? If so, how do I delete the appropriate things in the .yaml? Or how do I tell Cassandra to look for my storage-conf.xml file? A few things I have tried: renaming the cassandra.yaml file. What happens is that cassandra will not load. If i rename the storage-conf.xml, cassandra does load. When I installed Cassandra, it did not come with a storage-conf.xml file. I had to grab it off the apache wiki.

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  • Cassandra and asp.net (C#)

    - by Sergey Osypchuk
    I am interested to create portal on cassandra services, since I faced some performance and scale issues starting from 1 million of records. Definitely, it could be solved, but I am interested on other options. My main issues is cost of updating all necessary indexes, to make reading fast. First, is cassandra is good way for asp.net programmers? I mean, maybe there is some other projects, which worth to take a look And second, can you provide any documentation samples on how to start with cassandra programming from C#?

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  • How do I insert a row with Perl's Net::Cassandra::Easy?

    - by knorv
    When using the Perl module Net::Cassandra::Easy to interface with Cassandra I use the following code to read colums col[123] from rows row[123] in column-family Standard1: my $cassandra = Net::Cassandra::Easy->new(keyspace => 'Keyspace1', server => 'localhost'); $cassandra->connect(); my $result = $cassandra->get(['row1', 'row2', 'row3'], family => 'Standard1', byname => ['col1', 'col2', 'col3']); This works as expected. However, when trying to insert row row1 with .. $result = $cassandra->mutate(['row1'], family => 'Standard1', insertions => { "col1" => "Value to set." }); .. I get the error message Can't use string ("0") as a SCALAR ref while "strict refs" in use at .../Net/GenThrift/Thrift/BinaryProtocol.pm line 376. What am I doing wrong?

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  • Querying a Cassandra column family for rows that have not been updated in X days

    - by knorv
    I'm moving an existing MySQL based application over to Cassandra. So far finding the equivalent Cassandra data model has been quite easy, but I've stumbled on the following problem for which I'd appreciate some input: Consider a MySQL table holding millions of entities: CREATE TABLE entities ( id INT AUTO_INCREMENT NOT NULL, entity_information VARCHAR(...), entity_last_updated DATETIME, PRIMARY KEY (id), KEY (entity_last_updated) ); The table is regularly queried for entities that need to be updated: SELECT id FROM entities WHERE entity_last_updated IS NULL OR entity_last_updated < DATE_ADD(NOW(), INTERVAL -7*24 HOUR) ORDER BY entity_last_updated ASC; The entities returned by this queries are then updated using the following query: UPDATE entities SET entity_information = ?, entity_last_updated = NOW() WHERE id = ?; What would be the corresponding Cassandra data model that would allow me to store the given information and effectively query the entities table for entities that need to be updated (that is: entities that have not been updated in the last seven days)?

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  • How to prevent traffic to/from a slow Cassandra node using Python

    - by Sergio Ayestarán
    Intro: I have a Python application using a Cassandra 1.2.4 cluster with a replication factor of 3, all reads and writes are done with a consistency level of 2. To access the cluster I use the CQL library. The Cassandra cluster is running on rackspace's virtual servers. The problem: From time to time one of the nodes can become slower than usual, in this case I want to be able to detect this situation and prevent making requests to the slow node and if possible to stop using it at all (this should theoretically be possible since the RF is 3 and the CL is 2 for every single request). The questions: What's the best way of detecting the slow node from a Python application? Is there a way to stop using one of the Cassandra nodes from Python in this scenario without human intervention? Thanks in advance!

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  • Is Using Python to MapReduce for Cassandra Dumb?

    - by UltimateBrent
    Since Cassandra doesn't have MapReduce built in yet (I think it's coming in 0.7), is it dumb to try and MapReduce with my Python client or should I just use CouchDB or Mongo or something? The application is stats collection, so I need to be able to sum values with grouping to increment counters. I'm not, but pretend I'm making Google analytics so I want to keep track of which browsers appear, which pages they went to, and visits vs. pageviews. I would just atomically update my counters on write, but Cassandra isn't very good at counters either. May Cassandra just isn't the right choice for this? Thanks!

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  • Cassandra or MySQL/PostgreSQL?

    - by Ivri
    Hi! I have huge database (kinda wordnet). And want to know if it's easier to use Cassandra instead of MySQL|PostrgreSQL All my life I was using MySQL and PostrgreSQL and I could easily think in terms of relational algebra, but several weeks ago I learned about cassandra and that it's used in facebook and twitter. Is it more convenient? What DBMS are usually used nowadays to store social net's data, relationships between objects, wordnet?

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  • Creating application using rails 2.3.5 and cassandra database

    - by Joshi
    hi all, Pls guide me how to create rails application using rails 2.3.5 and cassandra database as rails 2.3.5 supports mysql, sqllite etc. I typed in the command prompt like this $ rails -d cassandra myapp Databases supported for preconfiguration are: mysql, oracle, postgresql, sqlite2, sqlite3, frontbase, ibm_db So pls help me in this regard

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  • Cassandra replication system - how it works

    - by inquisitor
    Does cassandra replicates only on write procedure (with choosen consistency level)? Is there any auto-replicate option for absent nodes, if i want symetric data in every node? If I plug in new node to cluster there is no auto replication - how to sync data from others nodes with new one? If I want replication like multimaster (2 nodes) with slave backup (1 node) known from MySQL, what is the proper logic setup and manage that on cassandra (3 nodes)? How about two nodes?

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  • How are Cassandra's 0.7 Secondary Indexes stored?

    - by user574793
    We have been using Cassandra 0.6 and now have Column Families with millions of keys. We are interested in using the new Secondary Index feature available in the 0.7 but couldn't find any documentation on how the new index is stored. Is there any disk-space limitation or is the index stored similar to keys in that it's spread over multiple nodes? I've tried combing through the Cassandra site for an answer but to no avail.

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  • Fetching Cassandra row keys

    - by knorv
    Assume a Cassandra datastore with 20 rows, with row keys named "r1" .. "r20". Questions: How do I fetch the row keys of the first ten rows (r1 to r10)? How do I fetch the row keys of the next ten rows (r11 to r20)? I'm looking for the Cassandra analogy to: SELECT row_key FROM table LIMIT 0, 10; SELECT row_key FROM table LIMIT 10, 10;

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  • Cassandra hot keyspace structure change

    - by Pierre
    Hello. I'm currently running a 12-node Cassandra cluster storing 4TB of data, with a replication factor set to 3. For the needs of an application update, we need to change the configuration of our keyspace, and we'd like to avoid any downtime if possible. I read on a mailing list that the best way to do it is to: Kill cassandra process on one server of the cluster Start it again, wait for the commit log to be written on the disk, and kill it again Make the modifications in the storage.xml file Rename or delete the files in the data directories according to the changes we made Start cassandra Goto 1 with next server on the list My questions would be: Did I understand the process well? Is there any risk of data corruption? During the process, there will be servers with different versions of the storage.xml file in the same cluser, same keyspace. Is it a problem? Same question as above if we not only add, rename and remove ColumnFamilies, but if we change the CompareWith parameter / transform an existing column family into a super one. Or do we need to change the name? Thank you for your answers. It's the first time I'll do this, and I'm a little bit scared.

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