使用leading和use_nl可以设置表的查询顺序,来加快查询速度, 比如有a,b,c,d四张表,a表的数据最少,如下设置 select /*+ leading(a) use_nl(a,b,c,d) index(a.id)*/ a.id from A 一般会将小表列为第一位 使用index直接匹配索引来查询数据提交查询速度...
关于USE_NL、USE_HASH、USE_MERGE: 我测试的是10g,三者只需填写表名作为参数,无顺序需要,应该是Oracle自动选择驱动表。 但是、可以用LEADING或ORDERED指定顺序。 (注意)INDEX的使用影响的是表自身的查询;USE_NL、USE_HASH、USE_MERGE影响的是表之间的连接。 详细参考:http://hi.baidu.com/di_wan/modify/blog/...
SELECT /*+ ORDERED INDEX (b, jl_br_balances_n1) USE_NL (j b)USE_NL (glcc glf) USE_MERGE (gp gsb) */b.application_id, b.set_of_books_id ,b.personnel_id, p.vendor_id Personnel,p.segment1 PersonnelNumber, p.vendor_name NameFROM jl_br_journals j, jl_br_balances b,gl_code_...
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65、AUDIT, COMMENT, DELETE, GRANT, INDEX, INSERT, LOCK, RENAME, SELECT, UPDATE, REFERENCES, and EXECUTE. Positions 14, 15, and 16 are reserved for future use. The characters are: - for none, S for success, F for failure, and B for both).COMMENT_TEXTVARCHAR2(4000)Text comment on th...
哦,原来如此,Oracle的确非常灵活,可以通过各种Hint来控制优化器产生不同的执行计划。例如,你想让Oracle走哪个索引,就可以用Hint: /*+ USE_INDEX(表名 索引名) */,你想让Oracle走全表扫描,就可以用Hint: /*+ FULL(表名) */。 的确,这几位银行的开发人员水平非常高,非常熟悉自己的数据分布情况和访问方式,广...
SQL>select index_name,index_type,table_name from user_indexes where table_name='表名'; 修改oracle时间格式: SQL> alter session set nls_date_format='YYYY-MM-DD HH24:MI:SS'; 指定开启某个监听: SQL>lsnrctl start orc5_lisenter(此处是当初建监听时创建的监听名) ...
alter indexCC.IDX_T_MATCH_IDmonitoring usage; 索引监控一般也不会只监控一个索引,一个表或者多个表甚至整个 SCHEMA 的索引都需要监控。如下使用 DBA 用户查到的 T_MATCH 表的所有索引都需要监控,则执行如下 SQL 的输出则可以监控整个表的索引使用情况。
And the database can still use it. This is because it can filter the rows in the index. This is often faster than full scanning the table.*Starting in 11.2.0.2, Oracle Database can use function-based indexes to process queries without the function in the where clause. This happens in ...
It seems (not confirmed from Oracle officially) LIKEC query doesn't use index at all, you get always full table scan that is costly when number of rows starts to grow. Like queries uses index as expected with same parameters. Change was done when fixing#5985 ...