
恆逸資訊資深講師
申建忠
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【專家開講】為什麼Oracle不使用我的索引(1)
1.首先建立測試環境
SQL> create table t1 as select * from all_objects;
SQL> create index t1_fidx on t1(substr(object_name,3,6);
SQL> execute dbms_stats.gather_table_stats('HR','T1',cascade=>true);
2.開始測試
SQL> select substr(object_name,3,6) from t1 where object_id=10000;
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