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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