点击(此处)折叠或打开

--执行drop_customers_indexes.sql, 删除除主键索引外的所有索引.
sh@TESTDB11>@drop_customers_indexes.sql
--在2个列上分别创建索引
CREATE INDEX idx_cust_last_name ON customers(cust_last_name) NOLOGGING COMPUTE STATISTICS;
CREATE INDEX idx_cust_first_name ON customers(cust_first_name) NOLOGGING COMPUTE STATISTICS;
--query10.sql
--优化程序可以同时使用这2个索引,但最终的成本不如使用复合索引低.
SET ECHO ON
SET TIMING ON
SET AUTOTRACE TRACEONLY
SET PAGESIZE 1000
@flush.sql
SELECT /*+ INDEX_JOIN(c idx_cust_first_name idx_cust_last_name) */ c.cust_last_name, c.cust_first_name FROM customers c;
SET TIMING OFF
SET AUTOTRACE OFF
--执行query10.sql
sh@TESTDB11>@query10.sql

ITPub博客

课程实践（二）续