Indexing

HI,

Simply - you need to index those columns (or groups of columns - compound indexes) that the the queries on the database search or sort on.

An index is effectivly a seperate table presorted on the index field pointing to the primary key of the table (which is already an automatic index)

For example, in a phone book, you would need to index on [Surname, Firstname] - therwise a search or sort would need to hunt through all records in the table.

As a more complex example, in a yellow pages, you would need additional indexes on town and business type.

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Maintaining indicies adds an overhead to the database, but that's small in comparison to the speed ups obtained on queries against them.

Posted By: fleckmatic, May 11, 19:07:25