Editing Database engine (section)

===Data structures===
{{Main|Database storage structures}}
A data structure is an abstract construct that embeds data in a well defined manner. An efficient data structure allows manipulation of the data in efficient ways. The data manipulation may include data insertion, deletion, updating and retrieval in various modes. A certain data structure type may be very effective in certain operations, and very ineffective in others. A data structure type is selected upon DBMS development to best meet the operations needed for the types of data it contains. Type of data structure selected for a certain task typically also takes into consideration the type of storage it resides in (e.g., speed of access, minimal size of storage chunk accessed, etc.). In some DBMSs database administrators have the flexibility to select among options of data structures to contain user data for performance reasons. Sometimes the data structures have selectable parameters to tune the database performance.

Databases may store data in many data structure types.<ref name="Physical Database Design">{{cite book|last1=Lightstone |first1=S. |first2=T. |last2=Teorey |first3=T. |last3=Nadeau |title=Physical Database Design: the database professional's guide to exploiting indexes, views, storage, and more |publisher=Morgan Kaufmann Press |year=2007 |isbn=978-0-12-369389-1 |ref=none}}</ref> Common examples are the following:
*ordered/unordered [[flat file database|flat files]]
*[[hash table]]s
*[[B+ tree]]s
*[[ISAM]]
*[[heap (data structure)|heaps]]