Cassandra Concepts: Difference between revisions

From NovaOrdis Knowledge Base
Jump to navigation Jump to search
No edit summary
 
(11 intermediate revisions by the same user not shown)
Line 24: Line 24:
==Replication Factor==
==Replication Factor==
==Replica Placement Strategy==
==Replica Placement Strategy==
==Column Family==
 
===Simple Strategy===


==Keyspace Operations==
==Keyspace Operations==
* [[Cassandra_Operations#Keyspace_Operations|List Keyspaces]]
* [[Cassandra_Operations#Keyspace_Operations|List Keyspaces]]
* [[Cassandra_Operations#Keyspace_Operations|Describe a Keyspace]]
* [[Cassandra_Operations#Keyspace_Operations|Describe a Keyspace]]


=Column Family=
<span id='Table'></span>A column family is the equivalent of a '''table''' in a relational database. Each column family (table) contains a collection of [[#Row|rows]], arranged logically in a map with the following structure:


Map<[[#Row_Key|RowKey]], SortedMap<[[#Column_Key|ColumnKey]], [[#Column_Value|ColumnValue]]>>


==Partition Key==
==Primary Key==


=Table=
==Row==


=Row=
==Row Key==


=Column=
==Column==


=Partition Key=
A column is a data structure that contains a [[#Column_Name|column name]], a [[#Column_Value|value]] and a [[#Column_Timestamp|timestamp]].
===Column Key===
===Column Name===
===Column Value===
===Column Timestamp===


Has primary key, or lookup key semantics.
=Java Support=
{{External|https://www.baeldung.com/cassandra-with-java}}

Latest revision as of 21:07, 25 September 2019

Internal

Overview

Cassandra is NoSQL a key-value database. It provides continuous availability with no single point of failure. The database uses a ring design and consistent hashing. In a ring design there is no master node, all nodes are identical and communicate with each other as peers. This architecture allows it to scale horizontally, by incrementally adding nodes with no reconfiguration. Provides good performance for large amounts of data.

CQL

Cassandra Query Language

SELECT "email" FROM "user_tweets" WHERE "username" = 'john';

Cluster

A cluster is a set of nodes (or data centers) deployed in a ring architecture. A cluster has a name, which will be used by participating nodes.

Node

Keyspace

The equivalent of a schema of relational database. The keyspace is the outermost container for data. A keyspace is characterized by its replication factor, replica placement strategy and its column families.

Replication Factor

Replica Placement Strategy

Simple Strategy

Keyspace Operations

Column Family

A column family is the equivalent of a table in a relational database. Each column family (table) contains a collection of rows, arranged logically in a map with the following structure:

Map<RowKey, SortedMap<ColumnKey, ColumnValue>>

Partition Key

Primary Key

Row

Row Key

Column

A column is a data structure that contains a column name, a value and a timestamp.

Column Key

Column Name

Column Value

Column Timestamp

Java Support

https://www.baeldung.com/cassandra-with-java