http://blog.csdn.net/haiross/article/details/37905485

select * from v$version

>show parameter read_count;  

1. --查看和read_count相关的隐藏参数       
2. sys@SYBO2SZ> @hidden_para  
3. Enter value for para: read_count  
4.   
5. KSPPINM                               KSPPSTVL             DESCRIB  
6. -----------------------------------   -------------------- ---------------------------------------------  
7. _db_file_exec_read_count              48                   multiblock read count for regular clients  
8. _db_file_optimizer_read_count         8                    multiblock read count for regular clients  
9. _db_file_noncontig_mblock_read_count  11                   number of noncontiguous db blocks to be prefetched  
10. _sort_multiblock_read_count           2                    multi-block read count for sort  
11.