---查看块大小为8192byte
SQL> show parameter db_block_size
 
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_size                        integer     8192

---创建一个表，记录最大大小超过8192byte,则可以产生行迁链或行迁移
SQL> create table t_row_chain(a varchar2(4000),b varchar2(3000),c varchar2(4000));
 
Table created
 
SQL> insert into t_row_chain values('x','y','z');
 
1 row inserted
 
SQL> commit;
 
Commit complete
 
SQL> exec dbms_stats.gather_table_stats(user,'t_row_chain',cascade=>true);
 
PL/SQL procedure successfully completed
 
SQL> select table_name,chain_cnt from user_tables where table_name='T_ROW_CHAIN';
 
TABLE_NAME                      CHAIN_CNT
------------------------------ ----------
T_ROW_CHAIN                             0
 
SQL> update t_row_chain set a=rpad('a',4000,'c');
 
1 row updated
 
SQL> commit;
 
Commit complete
 
SQL> select length(a) from t_row_chain;
 
 LENGTH(A)
----------
      4000
 
SQL> update t_row_chain set b=rpad('a',3000,'c');
 
1 row updated
 
SQL> update t_row_chain set c=rpad('a',4000,'c');
 
1 row updated

SQL> commit;
 
Commit complete
 
--用dbms_stats不能查出行链接或行迁移
SQL>  exec dbms_stats.gather_table_stats(user,'t_row_chain',cascade=>true);
 
PL/SQL procedure successfully completed
 
SQL> select table_name,chain_cnt from user_tables where table_name='T_ROW_CHAIN';
 
TABLE_NAME                      CHAIN_CNT
------------------------------ ----------
T_ROW_CHAIN                             0

SQL> analyze table t_row_chain list chained rows;
 
analyze table t_row_chain list chained rows
 
ORA-01495: specified chain row table not found

--先创建存储行链接或行迁移的表
SQL> @D:\oracle11g_64bit\product\11.2.0\dbhome_1\RDBMS\ADMIN\utlchain.sql
 
Table created

SQL> analyze table t_row_chain list chained rows;
 
Table analyzed

---行链接产生了
SQL> select * from chained_rows;
 
OWNER_NAME                     TABLE_NAME                     CLUSTER_NAME                   PARTITION_NAME                 SUBPARTITION_NAME              HEAD_ROWID         ANALYZE_TIMESTAMP
------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------ -----------------
TBL_BCK                        T_ROW_CHAIN                                                                                  N/A                            AAASD5AAGAAAA4jAAA 2013-05-21 2224