The accuracy of an execution plan depends on the quality of the optimizer statistics.

This part contains the following chapters:

• Optimizer Statistics Concepts
  Oracle Database optimizer statistics describe details about the database and its objects.
• Histograms
  A histogram is a special type of column statistic that provides more detailed information about the data distribution in a table column. A histogram sorts values into "buckets," as you might sort coins into buckets.
• Configuring Options for Optimizer Statistics Gathering
  This chapter explains what optimizer statistics collection is and how to set statistics preferences.
• Gathering Optimizer Statistics
  This chapter explains how to use the DBMS_STATS.GATHER_*_STATS program units.
• Managing Extended Statistics
  DBMS_STATS enables you to collect extended statistics, which are statistics that can improve cardinality estimates when multiple predicates exist on different columns of a table, or when predicates use expressions.
• Controlling the Use of Optimizer Statistics
  Using DBMS_STATS, you can specify when and how the optimizer uses statistics.
• Managing Historical Optimizer Statistics
  This chapter how to retain, report on, and restore non-current statistics.
• Importing and Exporting Optimizer Statistics
  You can export and import optimizer statistics from the data dictionary to user-defined statistics tables. You can also copy statistics from one database to another database.
• Analyzing Statistics Using Optimizer Statistics Advisor
  Optimizer Statistics Advisor analyzes how optimizer statistics are gathered, and then makes recommendations.