A super column is a
tuple
In mathematics, a tuple is a finite sequence or ''ordered list'' of numbers or, more generally, mathematical objects, which are called the ''elements'' of the tuple. An -tuple is a tuple of elements, where is a non-negative integer. There is o ...
(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, key-value store, 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 math ...
of columns.
Similar to a regular
column family
A column family is a database 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 fam ...
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
JSON (JavaScript Object Notation, pronounced or ) is an open standard file format and electronic data interchange, data interchange format that uses Human-readable medium and data, human-readable text to store and transmit data objects consi ...
-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
A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member ...
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 h ...
*
Keyspace (distributed data store)
*
Super column family
A super column family is a NoSQL object that contains column families. It is a tuple (pair) that consists of a key–value pair, where the key is mapped to a value that are column families. In analogy with relational databases, a super column fami ...
References
External links
The Apache Cassandra data model
Data_management
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