继续看查询的第二种情况，包含表连接的情况：

SQL> CREATE TABLE T AS SELECT * FROM DBA_USERS;

表已创建。

SQL> CREATE TABLE T1 AS SELECT * FROM DBA_SOURCE;

表已创建。

SQL> ALTER TABLE T ADD CONSTRAINT PK_T PRIMARY KEY (USERNAME);

表已更改。

SQL> ALTER TABLE T1 ADD CONSTRAINT FK_T1_OWNER FOREIGN KEY (OWNER)
2 REFERENCES T(USERNAME);

表已更改。

SQL> CREATE INDEX IND_T1_OWNER ON T1(NAME);

索引已创建。

SQL> EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'T')

PL/SQL 过程已成功完成。

SQL> EXEC DBMS_STATS.GATHER_TABLE_STATS(USER, 'T1')

PL/SQL 过程已成功完成。

创建了T表和T1表，默认情况下，HASH JOIN的效率要比NESTED LOOP高很多：

SQL> SET AUTOT TRACE
SQL> SELECT * FROM T, T1 WHERE T.USERNAME = T1.OWNER;

已选择96985行。

Execution Plan
----------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=844 Card=96985 Bytes=46164860)
1 0 HASH JOIN (Cost=844 Card=96985 Bytes=46164860)
2 1 TABLE ACCESS (FULL) OF 'T' (Cost=2 Card=12 Bytes=1044)
3 1 TABLE ACCESS (FULL) OF 'T1' (Cost=826 Card=96985 Bytes=37727165)

Statistics
----------------------
39 recursive calls
0 db block gets
14475 consistent gets
7279 physical reads
0 redo size
37565579 bytes sent via SQL*Net to client
71618 bytes received via SQL*Net from client
6467 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
96985 rows processed

SQL> SELECT /*+ FIRST_ROWS */ * FROM T, T1 WHERE T.USERNAME = T1.OWNER;

已选择96985行。

Execution Plan
----------------------
0 SELECT STATEMENT Optimizer=HINT: FIRST_ROWS (Cost=97811 Card=96985 Bytes=46164860)
1 0 NESTED LOOPS (Cost=97811 Card=96985 Bytes=46164860)
2 1 TABLE ACCESS (FULL) OF 'T1' (Cost=826 Card=96985 Bytes=37727165)
3 1 TABLE ACCESS (BY INDEX ROWID) OF 'T' (Cost=1 Card=1 Bytes=87)
4 3 INDEX (UNIQUE SCAN) OF 'PK_T' (UNIQUE)

Statistics
----------------------
0 recursive calls
0 db block gets
117917 consistent gets
7268 physical reads
0 redo size
37565579 bytes sent via SQL*Net to client
71618 bytes received via SQL*Net from client
6467 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
96985 rows processed

但是如果分页查询的内层是这种连接查询的话，使用NESTED LOOP可以更快的得到前N条记录。