Oracle索引原理

Execution Plan 0 SELECT STATEMENT Optimizer=CHOOSE(Cost=4 Card=1 Bytes=5) 1 0 SORT(AGGREGATE) 2 1 INDEX(FAST FULL SCAN) OF 'SKIP1'(NON-UNIQUE) Statistics 6826 consistent gets 6819 physical reads select /*+ index(emp5 skip1)*/ count(*) from emp5 where empno=7900; Elapsed:00:00:00.56 Execution Plan 0 SELECT STATEMENT Optimizer=CHOOSE(Cost=6 Card=1 Bytes=5) 1 0 SORT(AGGREGATE) 2 1 INDEX(SKIP SCAN) OF 'SKIP1'(NON-UNIQUE) Statistics 21 consistent gets 17 physical reads [10] 索引的类型 B-树索引 位图索引 HASH索引 索引编排表 反转键索引 基于函数的索引 分区索引 本地和全局索引