Views let you tailor access to data in the database. Tailoring access serves several purposes:
Efficient resource use Regular views do not require additional storage space for data; they are recomputed each time you invoke them. Materialized views require disk space, but do not need to be recomputed each time they are invoked. Materialized views can improve response time in environments where the database is large, and the database server processes frequent, repetitive requests to join the same tables.
Improved security By allowing access to only the information that is relevant.
Improved usability By presenting users and application developers with data in a more easily understood form than in the base tables.
Improved consistency By centralizing the definition of common queries in the database.
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