跪求索引问题 alter table 表名 add constraint 索引名 primary key (字段名) 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 没有啊.下面是测试:SQL> set serverout onSQL> set autotrace on SQL> set autotrace traceonlySQL> create table testd 2 ( 3 id number primary key, 4 name varchar2(200) 5 ) 6 tablespace cux;Table created.SQL> insert into testd select a.user_id ,a.user_name from fnd_user a;483 rows created.Execution Plan---------------------------------------------------------- 0 INSERT STATEMENT Optimizer=CHOOSE (Cost=5 Card=450 Bytes=495 0) 1 0 TABLE ACCESS (FULL) OF 'FND_USER' (Cost=5 Card=450 Bytes=4 950)Statistics---------------------------------------------------------- 44 recursive calls 26 db block gets 35 consistent gets 24 physical reads 20908 redo size 351 bytes sent via SQL*Net to client 596 bytes received via SQL*Net from client 4 SQL*Net roundtrips to/from client 4 sorts (memory) 0 sorts (disk) 483 rows processedSQL> commit;Commit complete.SQL> select * from fnd_user a where a.user_id=1055;Execution Plan---------------------------------------------------------- 0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1 Bytes=216) 1 0 TABLE ACCESS (BY INDEX ROWID) OF 'FND_USER' (Cost=1 Card=1 Bytes=216) 2 1 INDEX (UNIQUE SCAN) OF 'FND_USER_U1' (UNIQUE)Statistics---------------------------------------------------------- 0 recursive calls 0 db block gets 2 consistent gets 0 physical reads 0 redo size 1220 bytes sent via SQL*Net to client 308 bytes received via SQL*Net from client 2 SQL*Net roundtrips to/from client 0 sorts (memory) 0 sorts (disk) 1 rows processedSQL> 用不用索引是由oracle的优化器决定的,当然,有时并不是最优。可以使用hints来强制优化器来使用索引:select /*+ INDEX(aa) */ * from temp where aa = 'sdfdf'; 同意kongkongye的说法:select /*+ INDEX(temp aa) */ * from temp where aa = 'sdfdf'; 数据查询的问题 如果将一个含有long类型的表的数据负责到相同结构的表中? 关于ORACLE数据导入的问题 如何在Oracle中建立DBLink? Oracle的端口问题? S(:)S Red Hat Linux 9 下安装 Oracle 9i R2 出错 快帮帮忙,sql语句问题 关于把vb和oracle相连,请大家指教! 帮助 oracle初学者问题 oracle时间加减的函数?? 新手:oracle10比9i好很多吗?
SQL> set autotrace on
SQL> set autotrace traceonly
SQL> create table testd
2 (
3 id number primary key,
4 name varchar2(200)
5 )
6 tablespace cux;Table created.SQL> insert into testd select a.user_id ,a.user_name from fnd_user a;483 rows created.
Execution Plan
----------------------------------------------------------
0 INSERT STATEMENT Optimizer=CHOOSE (Cost=5 Card=450 Bytes=495
0) 1 0 TABLE ACCESS (FULL) OF 'FND_USER' (Cost=5 Card=450 Bytes=4
950)Statistics
----------------------------------------------------------
44 recursive calls
26 db block gets
35 consistent gets
24 physical reads
20908 redo size
351 bytes sent via SQL*Net to client
596 bytes received via SQL*Net from client
4 SQL*Net roundtrips to/from client
4 sorts (memory)
0 sorts (disk)
483 rows processedSQL> commit;Commit complete.SQL> select * from fnd_user a where a.user_id=1055;
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=1 Card=1 Bytes=216)
1 0 TABLE ACCESS (BY INDEX ROWID) OF 'FND_USER' (Cost=1 Card=1
Bytes=216) 2 1 INDEX (UNIQUE SCAN) OF 'FND_USER_U1' (UNIQUE)
Statistics
----------------------------------------------------------
0 recursive calls
0 db block gets
2 consistent gets
0 physical reads
0 redo size
1220 bytes sent via SQL*Net to client
308 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
1 rows processedSQL>
可以使用hints来强制优化器来使用索引:select /*+ INDEX(aa) */ * from temp where aa = 'sdfdf';
select /*+ INDEX(temp aa) */ * from temp where aa = 'sdfdf';