Oracle includes numerous data structures to improve the speed of Oracle SQL queries. Taking advantage of the low cost of disk storage, Oracle includes many new indexing algorithms that dramatically increase the speed with which Oracle queries are serviced. This article explores the internals of Oracle indexing; reviews the standard b-tree index, bitmap indexes, function-based indexes, and index-only tables (IOTs); and demonstrates how these indexes may dramatically increase the speed of Oracle SQL queries.
Oracle uses indexes to avoid the need for large-table, full-table scans and disk sorts, which are required when the SQL optimizer cannot find an efficient way to service the SQL query. I begin our look at Oracle indexing with a review of standard Oracle b-tree index methodologies.
The Oracle b-tree index
The oldest and most popular type of Oracle indexing is a standard b-tree index, which excels at servicing simple queries. The b-tree index was introduced in the earliest releases of Oracle and remains widely used with Oracle.
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Turbocharge SQL with Advanced Oracle Indexing
