Cassandra Table

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A Cassandra Table is a column family table (of Cassandra columns) within a Cassandra keyspace (within a Cassandra instance).



References

2015

  • (Wikipedia, 2015) ⇒ http://en.wikipedia.org/wiki/Apache_Cassandra#Data_model Retrieved:2015-8-20.
    • Cassandra is essentially a hybrid between a key-value and a column-oriented (or tabular) database.

      :A column family (called "table" since CQL 3) resembles a table in an RDBMS. Column families contain rows and columns. Each row is uniquely identified by a row key. Each row has multiple columns, each of which has a name, value, and a timestamp. Unlike a table in an RDBMS, different rows in the same column family do not have to share the same set of columns, and a column may be added to one or multiple rows at any time.

      Each key in Cassandra corresponds to a value which is an object. Each key has values as columns, and columns are grouped together into sets called column families.

      Thus, each key identifies a row of a variable number of elements. These column families could be considered then as tables. A table in Cassandra is a distributed multi dimensional map indexed by a key.

      Furthermore, applications can specify the sort order of columns within a Super Column or Simple Column family.

2012

2011

  • http://en.wikipedia.org/wiki/Apache_Cassandra
    • … Cassandra provides a structured key-value store with tunable consistency.[1] Keys map to multiple values, which are grouped into column families. The column families are fixed when a Cassandra database is created, but columns can be added to a family at any time. Furthermore, columns are added only to specified keys, so different keys can have different numbers of columns in any given family.

      The values from a column family for each key are stored together. This makes Cassandra a hybrid data management system between a column-oriented DBMS and a row-oriented store.


  • http://wiki.apache.org/cassandra/DataModel
    • The Cassandra data model is designed for distributed data on a very large scale. It trades ACID-compliant data practices for important advantages in performance, availability, and operational manageability. …

      The basic concepts are:

      • Cluster: the machines (nodes) in a logical Cassandra instance. Clusters can contain multiple keyspaces.
      • Keyspace: a namespace for !ColumnFamilies, typically one per application.
      • !ColumnFamilies contain multiple columns, each of which has a name, value, and a timestamp, and which are referenced by row keys.
      • !SuperColumns can be thought of as columns that themselves have subcolumns.
    • We'll start from the bottom up, moving from the leaves of Cassandra's data structure (columns) up to the root of the tree (the cluster).

2009