<19>. /*+MERGE(TABLE)*/能够对视图的各个查询进行相应的合并.例如:SELECT /*+MERGE(V) */ A.EMP_NO,A.EMP_NAM,B.DPT_NO FROM BSEMPMS A (SELET DPT_NO,AVG(SAL) AS AVG_SAL FROM BSEMPMS B GROUP BY DPT_NO) V WHERE A.DPT_NO=V.DPT_NO AND A.SAL>V.AVG_SAL;
<20>. /*+NO_MERGE(TABLE)*/对于有可合并的视图不再合并.例如:SELECT /*+NO_MERGE(V) */ A.EMP_NO,A.EMP_NAM,B.DPT_NO FROM BSEMPMS A (SELET DPT_NO,AVG(SAL) AS AVG_SAL FROM BSEMPMS B GROUP BY DPT_NO) V WHERE A.DPT_NO=V.DPT_NO AND A.SAL>V.AVG_SAL;<21>. /*+ORDERED*/根据表出现在FROM中的顺序,ORDERED使ORACLE依此顺序对其连接.例如:SELECT /*+ORDERED*/ A.COL1,B.COL2,C.COL3 FROM TABLE1 A,TABLE2 B,TABLE3 CWHERE A.COL1=B.COL1 AND B.COL1=C.COL1;
<22>. /*+USE_NL(TABLE)*/将指定表与嵌套的连接的行源进行连接,并把指定表作为内部表.例如:SELECT /*+ORDERED USE_NL(BSEMPMS)*/ BSDPTMS.DPT_NO,BSEMPMS.EMP_NO,BSEMPMS.EMP_NAM FROM BSEMPMS,BSDPTMS WHERE BSEMPMS.DPT_NO=BSDPTMS.DPT_NO;
<23>. /*+USE_MERGE(TABLE)*/将指定的表与其他行源通过合并排序连接方式连接起来.例如:SELECT /*+USE_MERGE(BSEMPMS,BSDPTMS)*/ * FROM BSEMPMS,BSDPTMS WHEREBSEMPMS.DPT_NO=BSDPTMS.DPT_NO;
<24>. /*+USE_HASH(TABLE)*/将指定的表与其他行源通过哈希连接方式连接起来.例如:SELECT /*+USE_HASH(BSEMPMS,BSDPTMS)*/ * FROM BSEMPMS,BSDPTMS WHEREBSEMPMS.DPT_NO=BSDPTMS.DPT_NO;
<25>. /*+DRIVING_SITE(TABLE)*/强制与ORACLE所选择的位置不同的表进行查询执行.例如:SELECT /*+DRIVING_SITE(DEPT)*/ * FROM BSEMPMS,DEPT@BSDPTMS WHERE BSEMPMS.DPT_NO=DEPT.DPT_NO;
<26>. /*+LEADING(TABLE)*/将指定的表作为连接次序中的首表.<27>. /*+CACHE(TABLE)*/当进行全表扫描时,CACHE提示能够将表的检索块放置在缓冲区缓存中最近最少列表LRU的最近使用端例如:SELECT /*+FULL(BSEMPMS) CAHE(BSEMPMS) */ EMP_NAM FROM BSEMPMS;
<28>. /*+NOCACHE(TABLE)*/当进行全表扫描时,CACHE提示能够将表的检索块放置在缓冲区缓存中最近最少列表LRU的最近使用端例如:SELECT /*+FULL(BSEMPMS) NOCAHE(BSEMPMS) */ EMP_NAM FROM BSEMPMS;
<29>. /*+APPEND*/直接插入到表的最后,可以提高速度.insert /*+append*/ into test1 select * from test4 ;insert /*+append */ into emp nologging
<30>. /*+NOAPPEND*/通过在插入语句生存期内停止并行模式来启动常规插入.
insert /*+noappend*/ into test1 select * from test4 ;
<31>.parallel direct-load insert sql> alter session enable parallel dml; sql> insert /*+parallel(emp,2) */ into emp nologging sql> select * from emp_old;
