摘要： 组合索引的前缀和单列索引一致,走INDEX RANGE SCAN drop table TX1 purge; create table TX1 as select * from dba_objects; SQL> select count(*) from (select distinct objec 阅读全文

摘要： 问题同时取最大和最小导到效率变低 测试 1.分别取最大和最小 drop table TX1 purge; create table TX1 as select * from dba_objects; update TX1 set object_id=rownum; commit; alter tab 阅读全文