Editing Database engine (section)

===Data orientation and clustering===
In contrast to conventional row-orientation, relational databases can also be [[column-oriented DBMS|column-oriented]] or [[correlation database|correlational]] in the way they store data in any particular structure.

In general, substantial performance improvement is gained if different types of database objects that are usually utilized together are laid in storage in proximity, being "clustered". This usually allows to retrieve needed related objects from storage in minimum number of input operations (each sometimes substantially time-consuming). Even for in-memory databases clustering provides performance advantage due to common utilization of large caches for input-output operations in memory, with similar resulting behavior.

For example, it may be beneficial to cluster a record of an "item" in stock with all its respective "order" records. The decision of whether to cluster certain objects or not depends on the objects' utilization statistics, object sizes, caches sizes, storage types, etc.