Initialization Parameters, 120 of 188

OPTIMIZER_FEATURES_ENABLE

Features	Release
Features	8.0.0	8.0.3	8.0.4	8.0.5	8.0.6	8.1.0	8.1.3	8.1.4	8.1.5	8.1.6	8.1.7
Use of index fast full scans (Oracle8i Designing and Tuning for Performance, Oracle8i Concepts)			X	X	X	X	X	X	X	X
Consideration of bitmap access paths for tables with only B-tree indexes			X	X	X
Complex view merging (Oracle8i Concepts)			X	X	X
Push-join predicate feature (Oracle8i Designing and Tuning for Performance)			X	X	X
Subquery unnesting (Oracle8i SQL Reference)											X
Common subexpression elimination											X
Index joins (Oracle8i Designing and Tuning for Performance, Oracle8i Concepts)											X

Parameter type:	String
Parameter class:	Static
Default value:	8.1.6
Range of values:	8.0.0, 8.0.3, 8.0.4, 8.0.5, 8.0.6, 8.1.0, 8.1.3, 8.1.4, 8.1.5, 8.1.6, 8.1.7
`OPTIMIZER_FEATURES_ENABLE` lets you change the behavior of the Oracle optimizer based on a release number. For example, if you migrate your database from 8.0.5 to 8.1.5, but you want to keep the 8.0.5 optimizer behavior, you can do so by setting this parameter to 8.0.5. At another time, you can try the new enhancements introduced up to release 8.1.5 by setting the parameter to 8.1.5. Table 1-5 lists some optimizer features and indicates which release settings enables those features. The features listed in Table 1-5 are described in the documents indicated.