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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decommisioning and relaunching/rejoining a weird behaved node

Had weirdly almost double data on one node after a rebuild of it thougt token ownership was similar to other nodes ~7%. So I decommissioned it, remove all files (commitlog and sstables eta.) Launched ...
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Setup Cassandra Database

I have a very simple cassandra database with just one table containing the following records: device ID - long integer representing the device the 'value' came from - primary key tag ID ...
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customize permission in Cassandra

i want to grant user update permission in Table and deny delete permission for this user. Is there any way to accomplish this?
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Is there a configuration option that lets me limit the percent of a hard drive that Cassandra uses?

I'm doing some testing with a small hard disk and I'd like to basically stop Cassandra in its tracks if a write or compaction or any other service brings that usage of the disk above a certain ...
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18 views

Apache Cassandra 2.0.12 is not compactable with 2.1.X version

I am trying to upgrade my cassandra from C* 2.0.12 to C* 2.1.13 version. I am following the upgrade procedure as specified in DataStax doc As per the C* CHANGES.txt file, it's clear that upgrade to ...
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Datastax solr query

I have 1 dse search node in my little cluster. I can look for data using solr quey only from this node. Is it possible to execute solr query from not dse search node (with cassandra only) too? Thanks
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DSE Cassandra decimal type

I generated solrschema with dsetool on a table name seriesdata (its key is composed by seriesmetadata_id, initialtime; two decimal field). These fields are defined as DecimalStrField but they are ...
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Cassandra 2.0 notetool status does not agree on every node

Got a cassandra 2.0.17 cluster w/14 nodes each with 256 vnodes, data seems not evenly distributed within nodes FSes after loading data. But while currently running a repair on first node (never done ...
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37 views

Cassandra in a Public Cloud - Which Snitch?

I am planning on deploying Cassandra in a public cloud (like Amazon AWS). The cluster will span multiple zones and regions. The cluster will also require logical DC separation within a given region. ...
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Cassandra query performs differently at different times

I am using apache-cassandra-2.0.12 in production, with network topology strategy and ReplicationFactor : 3 in a cluster with 2 DC’s each contains 4 nodes While analyzing the response time for the ...
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102 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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16 views

Cassandra change replication factor hive datastore

I am trying to change replication factor of HiveMetaStore but I receive this message: cassandra@cqlsh:system> alter KEYSPACE HiveMetaStore with replication = {'class': ...
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143 views

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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28 views

Why does Cassandra recommend against creating an index on high-cardinality columns?

The Cassandra documentation states, Do not use an index in these situations: On high-cardinality columns because you then query a huge volume of records for a small number of results. See ...
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23 views

Cassandra one-to-many table design

I am new to Cassandra from 20 years of RDBMS, and over the last few days have been reading and watching everything I can get my hands on that applies to my situation. I'm sure this is a basic ...
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23 views

Cassandra filtering multiple items

I am attempting to learn Cassandra by taking my RDBMS database and create a nosql version of it. Forgive any mistakes I am just making a quick example so I can ask my question. Here is my ...
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1answer
21 views

How to predict new node allocation in a Cassandra cluster?

I have a 5-node Cassandra cluster. Each node has disk space of 5TB. The real usage for each node is around 2.5TB depending on allocations and compactions (some are around 2TB some around 2.8). I ...
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41 views

Slow select from one billion rows GreenPlum DB

I've created the following table on GreenPlum: CREATE TABLE data."CDR" ( mcc text, mnc text, lac text, cell text, from_number text, to_number text, cdr_time timestamp ...
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91 views

Migration from Cassandra 2.x to 3.x: schema_keyspaces table is gone. How do you query system keyspaces?

I just migrated from Cassandra 2.x to 3.x (specifically, 3.4). Now the system tables have completely changed, and these changes are not in the documentation. If you look at the current CQL docs for ...
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Cassandra Multi Datacenter Different Data Size

I have a cassandra cluster which consists of 2 datacenter. datacenter2 is only for live backup and added existing cluster for this purporse. After run rolling repair on each node, nodetool status ...
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Is making a recursive hard link of all files inside cassandra data file directory a safe way to back up the entire database?

I have a single node cassandra cluster running on my local machine. I want to back up my data file directory. My question is pretty simple. Say I was to search the entire data file directory and ...
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31 views

Cassandra cluster monitoring linux script

I have opscenter but I am also looking for having a Cassandra cluster monitoring script running locally on the cluster nodes. Simple "nodetool status" would be fine. Does anyone have a handy script ...
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1k views

Cassandra: maintenance

I am inexperienced with Cassandra, but I have some experience with SQL-based relational databases. I have been unable to find best practices information about how to maintain Cassandra once deployed. ...
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how to disable delete in replication Cassandra datastax

my previous scenario i used Sql server one instance in amazon for live and the second in local network for archiving by disable delete in replication can i do this in Cassandra or what best ...
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28 views

How to create multiple graphs with titanDB(+cassandra , +rexster) in the same machine?

I'm experimenting with TitanDB (with Cassandra as storage) + Rexter. I have used different storage.keyspace value for different graphs in Titanrexster-server.xml thn also i m not getting multiple ...
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122 views

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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193 views

How does the Cassandra distribute data?

I cannot find a detailed document on this anywhere, however, that being said, if anyone has an answer to my question, I would be extremely grateful. In regards to Cassandra's standard node ...
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Cassandra DB Schema for Article, Comment on Comment

What is the efficient way to store the comments on comments in Cassandra so that retrieval will be easy(just through the partition key) e.g. There is article and people can comment on that article. ...
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194 views

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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47 views

Appropriate Design For Notification System

I am using Cassandra to store a list of notifications that have been sent to a user. The few requirements I have are: Order the notifications for each user by time received (DESC) Be able to delete ...
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320 views

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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47 views

How to get Cassendra database dump with data

I need to get a dump(with data) from a remote Cassandra database. I was able to get database schema via following command. How can i get all data in the keyspace? I'm using Cassandra 1.1.9. echo -e ...
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63 views

Filter rows, but only select most recent row for each Id

I have some code that is processing a lot of tasks. These tasks are either connected to a user or an account. Each Task go through many statuses -> Queued, Started, Error, Postponed, Queued, Started, ...
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Do you have to run nodetool repair on every node?

Do you have to run nodetool repair on every node in a cluster, or do you only need to run it on one node, and from there Cassandra will take care of the rest?
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2k 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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9k views

What is a good way to copy data from one Cassandra ColumnFamily to another on the same Keyspace (like SQL's INSERT INTO)?

Trying to find a way to easily transfer all the rows from a Cassandra ColumnFamily/Table to another. The COPY command, as I understand, is a good option. However, as it dumps all the data to .csv on ...
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487 views

NoSQL : What is unstructured data?

we are currently running at the edge of resources with our mssql server based solution. We have now many traditional options regarding the next move to tackle the load: buy faster CPUs and IO ...
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1answer
1k views

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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184 views

A good dataset to experiment NoSQL databases [closed]

I need to do some experiments in HBase and Cassandra and to do that I need an adequate dataset. The dataset I'm looking for has to be large enough (i.e. more than 2GB) and the data in it has to be ...
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81 views

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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3k views

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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92 views

How to Query Properties of an Entity in Apache Cassandra

I am new to Apache Cassandra, and I would like to know how to create a table in which I can filter rows by non-key columns. In relational databases, I would simply create a table with an ID as a ...
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141 views

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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113 views

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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75 views

How Wide-columns databases achieve dynamic columns on the storage layout? [closed]

As known, in relational databases, when adding a new column, data must be reallocated (http://stackoverflow.com/questions/463677/alter-table-without-locking-the-table) to maintain a single row ...
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61 views

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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627 views

What is the Cassandra setting for coordinator timeouts for schema change queries?

In my testing, I've found that the write_request_timeout_in_ms setting does not have any bearing on the timeouts for CREATE TABLE or ALTER TABLE statements in CQL. For instance, I have it set to ...
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162 views

Database migration for Large Data Set from MySQL to NoSQL

I have an existing APP that has N types of products that is normalized with MySQL. Each types of products have over 500K skus, and one of them are in the in 2M currently. We are currently tracking on ...
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3k views

Cassandra row ordering best practice

I have a column family that store articles. I'll need to get those articles from the most recent to the oldest, getting them from Country, and of course the ability to limit the number of fetched ...