In the design of database management systems, the identity map pattern is a database access design pattern used to improve performance by providing a context-specific, in-memory cache to prevent duplicate retrieval of the same object data from the database.
If the requested data has already been loaded from the database, the identity map returns the same instance of the already instantiated object, but if it has not been loaded yet, it loads it and stores the new object in the map. In this way, it follows a similar principle to lazy loading.
There are four types of Identity Map
- Explicit
- Generic
- Session
- Class
Famous quotes containing the words identity, map and/or pattern:
“Having an identity at work separate from an identity at home means that the work role can help absorb some of the emotional shock of domestic distress. Even a mediocre performance at the office can help a person repair self-esteem damaged in domestic battles.”
—Faye J. Crosby (20th century)
“If all the ways I have been along were marked on a map and joined up with a line, it might represent a minotaur.”
—Pablo Picasso (1881–1973)
“Swift while the woof is whole,
turn now my spirit, swift,
and tear the pattern there,
the flowers so deftly wrought,
the border of sea-blue,
the sea-blue coast of home.”
—Hilda Doolittle (1886–1961)