Encoded vector index

A few years ago, IBM Research came-up with a new type of index called an Encoded Vector Index (EVI). The main benefits of using EVIs is that they takes less space than a traditional index and they are noticeably faster for certain types of queries.

An encoded vector index provides access to a database table by assigning codes to distinct key values and then representing these values in an array. The elements of the array can be 1, 2, or 4 bytes in length, depending on the number of distinct values that must be represented. Because of their compact size and relative simplicity, encoded vector indexes provide for faster scans that can be more easily processed in parallel.

You create encoded vector indexes by using the CREATE ENCODED VECTOR INDEX statement. See What are encoded vector indexes for information on the use and maintenance of encoded vector indexes. For additional information about accelerating your queries with encoded vector indexes , go to the DB2 Universal Database for iSeries web pages.