Indexes exist to help speed up queries. Having the proper columns indexed can reduce the logical I/Os for queries. However, creating an index to make one query run faster may not be a good solution. Begin by examining the SQL statements that are currently being run against the database. If the query can be adjusted, that would be a logical first step. This is the same for both SQL Server and Oracle platforms.

There are costs associated with data changes when the indexes are involved. The maintenance requirements should be considered. The performance gains of adding the index should be more than the cost of maintaining the index. Also, too many indexes can add to performance issues instead of resolving them. Indexes should be used selectively ...

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