Apache Cassandra is an open source distributed database management system. It is designed to handle very large amounts of data spread out across many commodity servers while providing a highly available service with no single point of failure. It is a NoSQL solution.

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Keeping rows ordered by counter value

I'm storing linked words in a Cassandra v2 cluster and I'm having a hard time doing efficient reads. I'm trying to fetch the top X rows with the highest counter value. Cassandra doesn't store the ...
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Modeling Graph Data in Cassandra DB

I want to use Apache Cassandra to store a large amount of graph data according to a property graph model. The model contains the following entities: Vertices: Contains a map of key/value pairs ...
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Cassandra: memtable_offheap_space_in_mb and memtable_cleanup_threshold

I use C* v2.1.2 do write only workload (into one column family) and experiment with offheap-objects memtable space. I set parameters to: memtable_offheap_space_in_mb = 51200 # 50Gb ...
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Upgrading Cassandra

my Cassandra version is 1.2.4 and i'm trying to upgrade it to 2.0.5 and i know that in the first part i have to upgrade it to 1.0.14 and after that try to upgrade it to the 2.0.5 , when I try to run ...
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973 views

How to create multiple graphs with TitanDB (+Cassandra) in the same machine?

I'm experimenting with TitanDB (with Cassandra as storage) + Rexter. I've been reading the documentation during hours and trying to create multiple graph DBs on the same machine, but I didn't find ...
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Cassandra: Request did not complete within rpc_timeout

i was working with Cassandra 1.2.4 probably, after restoring some key-space when i tried to query in a key-space it gave me Request did not complete within rpc_timeout so i checked system.log & ...
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Update a Record in Cassandra

I'm having the following query while updating a particular record. I've a user Column Family CF as follow:- class User(Model): user_id = UUID(default=uuid.uuid4,primary_key= True) date = ...
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Cassandra Deployement Architecture

I'm new to Cassandra. I have the responsibility to design a basic deployment architecture for a use case. I'd like to know if my solution is correct, and get advice and recommendations from you. Here ...
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Strugling with updating a cassandra row in FluentCassandra

I have this problem with using Fluent Cassandra in a test application. All I want to do is set the IsOnline field to true inside the SignIn method, but I keep getting the exception supercolumn ...
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What kind of database is Cassandra DB?

I was taking some courses to understand better the way Cassandra works (at academy.datastax.com) and by what I gathered it came to me that it is a Key Value Database because of the way it stores data ...
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Cassandra cluster monitoring

We using Nagios for our servers monitoring. Each web-environment have 1 cluster as backend - Cassanra 2.0. Each cluster have 3-5 nodes. Question is: I want write a plugin for Nagios, for Cassandra's ...
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cassandra in memory tables

I am planning to use Cassandra in memory tables for my particular work load. THe problem is I am worried if the node fails then what will happen to the data in memory that was not flushed to disk ? ...
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Cassandra Database limitation

why Cassandra is limited to 65535 records only when stored in batch and loop is encounters 20000 only? I have inserted 20,000 customers but it shows an error like too many values for built statement, ...
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Running Cassandra on Encypted filesystem

Looking for pointers for running Cassandra on a Linux File system encrypted by open source tools. Will this satisfy "data-at-rest" encryption ? Is the encryption transparent to Cassandra DB ...
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26 views

Cassandra - save file

I'm new with Cassandra, and even more - I never have such task for habitual RDMS systems, like MariaDB or Oracle. So, how can I store file in to Cassandra's table? Preferably using Python-driver, but ...
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How to connect Cassandra database with Chicago Boss Application?

My cassandra database is on a VMware server. The problem is that I don't find any database adapter which can help me in connecting my cassandra database with my chicago boss(a web framework in Erlang) ...
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30 views

What is the graveyard compaction in cassandra?

Cassandra noob here. While going through the documentation etc, I'm repetitevely finding references to graveyard compaction (and occasionally tombstones), example: $ cassandra-cli [default@unknown] ...
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6 views

Middle of Node replace

I had to replace a dead node, now I have two other nodes that are down. Can I shutdown the entire cluster in the middle of replace node process? If I resume do I have remove the JVM_OPTS=$JVM_OPTS ...
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48 views

Data modeling question on Cassandra DB

I'm trying to save events of a month for a user to my Cassandra DB instance. Each month the data will expire and will be removed. The data I try to model will contain user id, date of event and event ...
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Cassandra CL quorum giving inconsistent values

How is this even possible? cqlsh:keyspace> consistency Current consistency level is QUORUM. select * from email_idx where email='xxx@yyy.com'; email------------------- | user_id ...
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cassandra:request didn't complete with rpc_timeout

cassandra:request didn't complete with rpc_timeout.I Have set up a cassandra server of only one node and import 60 lacs record.but when we run select query it show error of rpc_timeout over 10000 ...
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71 views

How to apply updates in a “Fan out on write” architecture?

If I copy certain writes to different tables for faster read performance on certain queries(fan out on write), how should I design updates? Since the data is spread over different tables, I'm trying ...
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339 views

Cassandra cluster on Windows Machine

I am new to Cassandra, and have been trying to create a cluster using DevOps. When I add a node , I get the following error: Error provisioning cluster: Unable to SSH to some of the hosts ...