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SLIDE #06             INGRES: SECONDARY INDEX

Relations may be have secondary indexes, besides the primary index.

The index on command let us specify a secondary key. For each
secondary key, Ingres creates a "secondary relation". 

For example:

   index on student is ageidx(age)

let us define age as a secondary index. Ingres uses the secondary relation,
ageidx, to access the primary relation.