A partition is a division of a logical Database or its constituting elements into distinct independent parts.

Database partitioning is normally done for manageability, performance or availability reasons.

The partitioning can be done by either building separate smaller databases (each with its own Table (database), Index (database), and transaction), or by splitting selected elements, for example just one table.

=Partitioning criteria=

Current high end relational database management systems provide for different criteria to split the database. They take a partitioning key and assign a partition based on certain criteria. Common criteria are:

; Range partitioning : Selects a partion by determining if the partitioning key is inside a certain range. An example could be a partition for all row (database) where the column (database) zipcode has a value between 70000 and 79999. ; List partitioning : A partition is assigned a list of values. If the partitioning key has one of these values, the partition is chosen. For example all rows where the column Country is either Iceland, Norway, Sweden, Finland or Denmark could build a partition for the Nordic countries. ; Hash partitioning : The value of a hash function determines membership in a partition. Assuming there are four partitions, the hash function could return a value between 0 and 3.

Composite partitioning allows for certain combinations of the above partitioning schemes, by for example first applying a range partitioning and then a hash partitioning.

=See also=

=External links=