SQL并行查询

   alter session enable parallel dml

或
   execute immediate 'alter session enable parallel dml'; 修改会话并行DML     
   select /*+parallel(a,4)*/ * from table_name a          
   select /*+parallel(a,4) parallel(b,4) parallel(c,4)*/ a.*,b.*,c.*  from table_name1 a,table_name2 b,table_name c      
   insert /*+parallel(t,4)*/ into table_name t