Tag: Cassandra

C*, Cardinality, Cassandra, Database Index, Encapsulation, Enterprise Java Software Developer, Generics, Java, JPA, JPQL, Managed beans, Managed objects, Materialized View, Object oriented programming, Object Persistence, Object query language, Object relational mapping, Open Source, OQL, ORM, Primary Key, Query, SQL, Unique Key

Distributed Object Persistence API for Cassandra

Object persistence API for Cassandra.

Cardinality, Cassandra, Clustering Key, Database Index, Partitioning Key, Primary Key, Query

Cassandra node vs partition: A simple explanation

As explained in How does Cassandra store data? – A simple explanation Cassandra uses partitioning key (the first part of primary key) to store a record into a partition on a node. Prior to version 1.2, one server = one node. That is each machine was assigned to a range of values, so that the entire cluster covered … Continue reading Cassandra node vs partition: A simple explanation

Cardinality, Cassandra, Clustering Key, Database Index, J2EE, Java, JEE, JPQL, Partitioning Key, Primary Key, Query, SQL, Unique Key

Cassandra Primary Key = ((Partitioning Key), Clustering Key): A simple explanation

Cassandra primary key (a unique identifier for a row) is made up of two parts - 1) one or more partitioning columns and 2) zero or more clustering columns. To search a table without any indexes, all partitioning columns must be provided to avoid error message: Cannot execute this query as it might involve data filtering … Continue reading Cassandra Primary Key = ((Partitioning Key), Clustering Key): A simple explanation

Cassandra, Java, JEE, JPQL, SQL

How does Cassandra store data? – A simple explanation

Every time a record is inserted into Cassandra - it follows the write-path as per the diagram above. First, the record is written to a commit log (on disk). All records irrespective of schema tables  are written to the commit log. The commit log enables recovery of memtable in case of hardware failure. Second,  the … Continue reading How does Cassandra store data? – A simple explanation