A super column is a
tuple
In mathematics, a tuple is a finite ordered list (sequence) of elements. An -tuple is a sequence (or ordered list) of elements, where is a non-negative integer. There is only one 0-tuple, referred to as ''the empty tuple''. An -tuple is defi ...
(a pair) with a binary super column name and a value that maps it to many columns. They consist of a
key–value pairs, where the values are columns. Theoretically speaking, super columns are (
sorted)
associative array
In computer science, an associative array, map, symbol table, or dictionary is an abstract data type that stores a collection of (key, value) pairs, such that each possible key appears at most once in the collection. In mathematical terms an ...
of columns.
Similar to a regular
column family where a row is a sorted map of column names and column values, a row in a super column family is a sorted map of super column names that maps to column names and column values.
A super column is part of a
keyspace together with other super columns and column families, and columns.
Code example
Written in the
JSON-like syntax, a super column definition can be like this:
Where:
"databases" are
keyspace;
"Cassandra" and "HBase" are rowKeys;
"name" and "address" are ''super column'' names;
"firstName", "city", "age", etc. are
column names.
See also
*
Column (data store)
A column of a distributed data store is a NoSQL object of the lowest level in a keyspace. It is a tuple (a key–value pair) consisting of three elements:
* Unique name: Used to reference the column
* Value: The content of the column. It can ha ...
*
Keyspace (distributed data store)
*
Super column family
References
External links
The Apache Cassandra data model
Data_management
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