Optimizer_mode : RULE | FRIST_ROWS | ALL_ROWS | CHOOSE
COST : run by FTS Which don't need , Iespeacial under 3 tables jion
RULE : choose error index
FULL TABLE SCAN 临界条件:
1. sorted table -- > 40% rows need be seleced using FTS
2. unsorted table -- >7%rows need be selected using FTS
About driver table under RULE : 返回行最小的表should be put the frist position in where clause ，but COST auto choose driver table .
COST : need all tables and indexes be analyzed . dbms_utility.analyze_schema('schema_name','','','FOR TABLE FOR ALL INDEXES')
CBO SQL TIPS/*+ rule*/ /*+ full, table =xxx parallel = nn *//*+ table =xxx index=xxx *//*+ frist_rows *//*+ use_hash */
CUSOR_SHARING =FORCE
OUTLINE : hard sql execute plan
TOOLS : XPLAN , TIMING ON
oracleHu 2005-10-28
