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Questions tagged [column-family]

A column family is a NoSQL object that contains columns of related data. It is a tuple (pair) that consists of a key-value pair, where the key is mapped to a value that is a set of columns. In analogy with relational databases, a column family is as a "table".

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If I write data into different column family of hbase concurrently, whether there is mutual influence

In my application, every thread is responsible for writing data into one column family, these threads may not start at the same time, but they may write data synchronously.
yi jiang
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Using rocksdb::Iterator and Column Family is not working

I have the following piece of code: rocksdb::DBWithTTL* db = ... rocksdb::WriteOptions writeOptions; rocksdb::ColumnFamilyHandle cfHandle = ... std::string keyPrefix = "prefix"; std::string key = keyPrefix + "_key"; std::string value =…
Mugen
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Transfer data from one column family db to another column family

I'm new to Cassandra and Column family database world.I have a scenario where I need to move data from one Column family database such as Scylla Database to another Column family database Datastax Cassandra.Amount of data to be transferred will be…
Balaji Reddy
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What are best practices for deleting/altering cassandra columns of collection data-type?

In our Cassandra table, every time we change data-types of "collection-type" columns it start causing issue. For example: For changing datatype from text to Map we do this: drop existing column wait for cassandra to assimilate this…
0biwan
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How can I skip HBase rows that are missing specific column family?

For example, a HBase table has columnFamilyA, columnFamilyB and columnFamilyC, for some rows, columnFamilyA does not have any column in it. I would like to scan the table and return only the rows that have at least one column in columnFamilyA. What…
user3483218
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How to join multiple data sources in Cassandra

I'm working for the first time with Cassandra and I have some doubts. My data sources are csv files. I have three: flights, airplane and airport. I will put the structure of each csv file to contextualize my problem. Airport ID_airport | airport |…
Pedro Cunha
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How to get column family and qualifier of a HBase Table

I want to use the following: List cells = sourcePut.get(CfBytes, QualBytes); But it is returning me an empty list, since I am not specifying the correct column family and/or correct qualifier. For my source table, how to view all column…
Arijit
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cassandra copy data from one columnfamily to another columnfamily from two different keyspaces

I am a newbie to cassandra. is there a way to copy data from one column family from a key space to another keyspace? We have an application, that generates new keyspaces of same column families. We are thinking to merge all them into one keyspace…
Divakar
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cassandra: inconsistent column families

Taken from the example in http://www.ibm.com/developerworks/library/os-apache-cassandra/. Suppose we are concerning with two entities: books and tags. A book has multiple tags, so the relationship between them is 1:M. According to the article, we…
user3839198
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Periodically receive "InvalidQueryException: unconfigured columnfamily documents"

We have an app that is basically polling periodically for changes every 1 minute, using Datastax c* driver 2.0.4 (also tried 2.1.0-beta1). We create a Session at app startup, specifying the keyspace, e.g. Session session =…
Tyson Norris
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understanding the code for inserting column family in Cassandra keyspace?

I am reading Cassandra- The definitive guide by E.Hewitt. I am in the fourth chapter where the author describes the code for sample Hotel application. The image from the book is given here for reference. Here is the method for inserting rowkeys in…
brain storm
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How to Create a Column family in a Selected Cluster in HBase

In cassandra hector API allow to create table on a selected cluster as follows. I want to do the same thing using HBase, can someone please help me out? This is how it can done using Cassandra : public void createColumnFamily(Cluster cluster,…
Chamika Kasun
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NoSQL (cassandra) data model for my project

I need to have your opinion on my design of data model for my project. My project is real-time recommendation system. There are some collections of recommendation algorithms. it means something like this: collection1 { algorithm1, algorithm5,…
Jan Bouchner
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No data relationships in big table databases?

If the relationships between the data are as important as the data itself (such as distance or path calculations), then don't use a column family/big table database. (Quoted from article Big data woes: Which database should I use? by Andrew…
Dominykas Mostauskis
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How do I get all the keys that are stored in the Cassandra 2.0.1 column family with scala using hector?

I have to enter some values with a key(suppose key1="1_100"), but before inserting the values i want to check that is key("1_100") is already inserted or not.I know it will replace the previous one, if exists. i only want to enter values if key is…
user2822316
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