There is nothing wrong in having a comma in a hint:
SQL> create table test_hint ( c1 number not null , c2 number);
Table created.
SQL>
SQL> create index testix1 on test_hint (c1);
Index created.
SQL>
SQL> set autotrace on explain;
SQL>
SQL> select * from test_hint a;
no rows selected
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE
1 0 TABLE ACCESS (FULL) OF 'TEST_HINT'
SQL>
SQL> select /*+ index(a,testix1) */ * from test_hint a;
no rows selected
Execution Plan
----------------------------------------------------------
0 SELECT STATEMENT Optimizer=CHOOSE (Cost=826 Card=164 Bytes=4
264)
1 0 TABLE ACCESS (BY INDEX ROWID) OF 'TEST_HINT' (Cost=826 Car
d=164 Bytes=4264)
2 1 INDEX (FULL SCAN) OF 'TESTIX1' (NON-UNIQUE) (Cost=26 Car
d=164)
Regards,
Waleed
-----Original Message-----
Sent: Sunday, September 01, 2002 9:28 PM
To: Multiple recipients of list ORACLE-L
Thanks all the responses.
It's the syntax error like Naveen said. Oracle didn't detect the error, it
just simply ignore the hints if the syntax is wrong.
Thanks again,
Chuan
-----Original Message-----
Sent: Friday, 30 August 2002 5:33 PM
To: Multiple recipients of list ORACLE-L
If you specify a hint Oracle is forced to use the index.
Your hint's syntax is wrong. USE - /*+ INDEX(test index_a) */
**** Don't use the comma ******* between the table name and the index name
Naveen
-----Original Message-----
Sent: Friday, August 30, 2002 12:33 PM
To: Multiple recipients of list ORACLE-L
Hi, All,
On a million row table, test, there is primary key on column a.
when I run select /*+ index (test,indx_a) */ a, b, c, from test, according
to Oracle, I should get the following explain plan.
TABLE ACCESS
BY INDEX ROWID test 1
INDEX
UNIQUE SCAN PK_test 1
But I acctucally got :
TABLE ACCESS
FULL test 1
The database optimizer mode is choose, and I gathered the statistics on
table and index using dbms_utitlity and analyze.
In the session level, I also set optimizer_mode=first_rows to push optimizer
to choose the index.
According to Oracle Doc "use hints to force the optimizer to use the optimal
execution plan.", to my understanding, the explain plan under such a
situation, should be the first one.
Does Oracle follow the hint? or to waht extents, it follows?
Appreciated if someone guides me to the right direction.
Chuan,
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