Questions tagged [cassandra]

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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utf8 errors retrieving strings from Cassandra

I have been tasked with fixing a problem seen occasionally in a Cassandra database when strings are retrieved, either programmatically or in CQLSH, and currently running with Cassandra version 2.1.15 ...
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38 views

Cassandra query response time degradation

I am experimenting with Cassandra on 4 sites with 2 nodes on each one. Have small network latency between them. I always query the data in DC where I inserted it. I see very strange behavior: when I ...
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Backup ScyllaDB/Cassandra remotely with compression

How can I backup ScyllaDB/Cassandra remotely? With PostgreSQL I can do something like this (backup, zip, transfer): mkdir -p tmp/backup OUTFILE=tmp/backup/db_backup_`date +%Y-%m-%d_%H%M%S`.sql.xz ...
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How to query on collection containing user defined data types in cassandra?

I am using Cassandra and I have created Type Participant as follows: CREATE TYPE soccer1.participant ( username text, participant_type text ); Table: CREATE TABLE soccer1.playground_table ( ...
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Cannot Connect to Cassandra on GCE

I just started learning how to use Cassandra, but at the moment I am trying to troubleshoot a small problem with GCE and Cassandra. I am not able to connect to it at all. I am using this Deployment ...
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Cassandra data modelling for IOT devices

We are building a micro service based IOT platform with a dashboard and views of various sensors etc. I have seen a few data modelling videos but I am not able to arrive at a good data model in ...
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239 views

Cassandra restore fails if sstableloader is used

Starting point: new cluster, DSE 6.7.4, C* 4.0.0.674 backed UP data, which was made by Opscenter snapshot backups to remote S3 bucket (1.5TB per each node) restoring data to new cluster needs to use ...
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Show cassandra help documentation in terminal instead of browser

I've just started playing around with Cassandra through the cqlsh cli. When using the help command for the topics the documentation opens in the browser. Is there a way to show the documentation in ...
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cassandra nodes have diff value

I have 3 node cluster, problem is that for some rows , updatetime column have different value on 3 node: like : 1st node : updated_on | 2018-08-22 17:01:30+0530 2nd node : updated_on ...
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OpsCenter missing in Datastax Cassandra for Windows

Following this guide within the Cassandra installer I should get OpsCenter too. But this screenshot https://www.datastax.com/wp-content/uploads/2012/01/dsc-win4.jpg doesn't match the current release (...
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SQL Join vs NoSQL Wide column

If we need to have 2 tables, one storing the author info(author_info), & another storing all the books info(book_info). author_info has authorId as it's primary key, whereas the book_info table ...
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149 views

Hints gc_grace and expirations

Have 3 node cluster. RF=3. Table with gc_grace_seconds = 120 secs. max_hints duration as default at 3 hours. inserted a row nodetool flush on all the 3 nodes bring down node 3 delete the inserted ...
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1k views

dropping a table does not delete the directories on the disk

I am just testing the drop table command in Cassandra 3.11. The sequence is as follows: Load data worth 10gb drop the table on the node, nodetool flush nodetool clearsnapshot nodetool cleanup ...
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How these conflicting scenarios will work in cassandra when one of the mode crashes?

Say we have two nodes(simple replica no sharding) i.e. N1,N2 with replication factor as 2. I am using default Read and write consistency levels i.e. R and W are 1 which means it will read/write from/...
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75 views

Replica model in Cassandra vs Mongo?

Say in Mongo we have one primary and two replica node(simple replica no sharding). Read and write request will be handled only primary node and replica will just backup the data in case of failover. ...
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857 views

Database latency vs throughput

I'm a bit confused by terms latency and throughput in case of databases. My understanding is that latency represents time needed to perform a single request (e.g. insert or select), while the ...
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Error while starting Cassandra 2.0.2 service

I am new to cassandra NoSQL database. When I tried to start cassandra I am getting bellow error. Command used to start. ./cassandra -f xss = -ea -javaagent:./../lib/jamm-0.2.5.jar -XX:+...
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68 views

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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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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2k 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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438 views

Cassandra cqlsh browser queries possible only in bytes

I am using Cassandra database through cqlsh client on Linux. I can make only queries with values given as bytes, but I would like to search with the client like in SQL where everything is Strings. ...
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32 views

Stopping N number of nodes of a Cassandra cluster running on a single machine using bash script

I have set up a Multi-Node cassandra (3.11) cluster (with N nodes) in a single Ubuntu machine. I have written a bash script which Creates N copies of conf folder Configures the cassandra yaml file ...
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582 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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1answer
571 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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77 views

Database software advice [closed]

I have this strange question. I'm building a service that stores information into one table. That table has 20 columns. My database will have many billion rows. Right now I'm using Cassandra, but it ...
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950 views

How can I generate Cassandra data model from a MySQL schema?

Is there a tool for generating a Cassandra model from a MySQL database?

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