请问一个left join的问题 不好意思,对oracle不怎么熟悉,执行计划结果出来了,但是看不懂,汗~主表A和子表B均建立了索引,作关联是指? 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 贴上实例语句和执行计划,其中Flowid是两个表关联的字段SQL> select A.Flowid from TGWMain A left join TGWXX B on A.Flowid=B.Flowid where B.userid='zys'Execution Plan---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=731 Card=1892 Bytes= 295152) 1 0 HASH JOIN (Cost=731 Card=1892 Bytes=295152) 2 1 TABLE ACCESS (FULL) OF 'TGWXX' (Cost=706 Card=1892 Bytes=196768) 3 1 TABLE ACCESS (FULL) OF 'TGWMAIN' (Cost=15 Card=3828 Bytes=199056)Statistics---------------------------------------------------------- 0 recursive calls 6 db block gets 4647 consistent gets 610 physical reads 0 redo size 219 bytes sent via SQL*Net to client 372 bytes received via SQL*Net from client 1 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 0 rows processed希望高手可以找到查找慢的原因 这是基于成本的优化,建议1.对A,B表对字段Flowid建立索引2.对B表的userid建立索引3.建议建完索引后分析表:analyze table A estimate statistics; 一个SQL写法的请教 java web程序员(2012届毕业生),希望加强下oracle学习。推荐下资料 行转列:动态语句返回游标的问题 oracle 查询模板(contains) 用sys登陆后怎么访问其他用户的系统表? DBMS_CHANGE_NOTIFICATION 问题,100分求答案 ORACLE 的session问题,立刻给分 oracle8.0.5在unixware上安装问题。急!! UPDATE 问题 如何进行数据库优化 请教大家一个有关数据库(附加)的问题?请赐教.. 显示日期问题
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=731 Card=1892 Bytes=
295152) 1 0 HASH JOIN (Cost=731 Card=1892 Bytes=295152)
2 1 TABLE ACCESS (FULL) OF 'TGWXX' (Cost=706 Card=1892
Bytes=196768) 3 1 TABLE ACCESS (FULL) OF 'TGWMAIN' (Cost=15 Card=3828
Bytes=199056)Statistics
----------------------------------------------------------
0 recursive calls
6 db block gets
4647 consistent gets
610 physical reads
0 redo size
219 bytes sent via SQL*Net to client
372 bytes received via SQL*Net from client
1 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
0 rows processed希望高手可以找到查找慢的原因
1.对A,B表对字段Flowid建立索引
2.对B表的userid建立索引
3.建议建完索引后分析表:analyze table A estimate statistics;