ORA-31693, ORA-02354 and ORA-01555 with Export Datapump，ora

ORA-31693, ORA-02354 and ORA-01555 with Export Datapump，ora-31693ora-02354

Symptoms

ORA-31693: Table data object "YXFUND"."MF_NOTTEXTANNOUNCEMENT" failed to load/unload and is being skipped due to error:
ORA-02354: error in exporting/importing data
ORA-01555: snapshot too old: rollback segment number 10 with name "_SYSSMU10$" too small 

cause

The old versions (consistent read) of the LOB can be specified by either the PCTVERSION or the RETENTION parameters.


For SecureFiles, only the RETENTION parameter can be specified.


for BasicFiles LOBs you can specify either PCTVERSION or RETENTION , but not both. 

- PCTVERSION : This parameter specifies the percentage of all used BasicFiles LOB data space that can be occupied by old versions of BasicFiles LOB data pages. Under 11g compatibility, this parameter is silently ignored when SecureFiles LOBs are created.

PCTVERSION is the default in manual undo mode and the default value is 10, meaning that older versions of the LOB data are not overwritten until they consume 10% of the overall LOB storage space.

You can specify the PCTVERSION parameter whether the database is running in manual or automatic undo mode. 

- RETENTION is the default in automatic undo mode. 

You can specify the RETENTION parameter only if the database is running in automatic undo mode. Oracle Database uses the value of the UNDO_RETENTION initialization parameter to determine the amount of committed undo data to retain in the database. In automatic undo mode, RETENTION is the default value unless you specify PCTVERSION. You cannot specify both PCTVERSION and RETENTION.

You can specify the optional settings after RETENTION only if you are using SecureFiles. 

You can see more details about the RETENTION parameter for SecureFiles and BasicFiles LOBs in the following link :

http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_tables.htm#ADLOB45282
RETENTION Parameter for SecureFiles LOBs

http://docs.oracle.com/cd/E11882_01/appdev.112/e18294/adlob_tables.htm#ADLOB45281
RETENTION Parameter for BasicFiles LOBs

solution

SQL>show parameter undo


NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
_gc_undo_affinity                    boolean                           FALSE
undo_management                      string                            AUTO
undo_retention                       integer                           900
undo_tablespace                      string                            UNDOTBS2


SQL> select max(maxquerylen) from v$undostat;


MAX(MAXQUERYLEN)
----------------
            1785


SQL> select COLUMN_NAME,PCTVERSION,RETENTION from dba_lobs where OWNER='YXFUND' and TABLE_NAME='MF_NOTTEXTANNOUNCEMENT';


COLUMN_NAM PCTVERSION  RETENTION
---------- ---------- ----------
CONTENT            10


SQL>ALTER SYSTEM SET UNDO_RETENTION = 7200 scope=both sid='*';


SQL>show parameter undo

NAME                                 TYPE                              VALUE
------------------------------------ --------------------------------- ------------------------------
_gc_undo_affinity                    boolean                           FALSE
undo_management                      string                            AUTO
undo_retention                       integer                           7200
undo_tablespace                      string                            UNDOTBS2




SQL> select COLUMN_NAME,PCTVERSION,RETENTION from dba_lobs where OWNER='YXFUND' and TABLE_NAME='MF_NOTTEXTANNOUNCEMENT';


COLUMN_NAM PCTVERSION  RETENTION
---------- ---------- ----------
CONTENT                     7200




SQL>alter table YXFUND.MF_NOTTEXTANNOUNCEMENT modify lob(CONTENT) (pctversion 5);


SQL>alter table YXFUND.MF_NOTTEXTANNOUNCEMENT modify lob(CONTENT) (retention);


参考my oracle support ：ORA-31693, ORA-02354 and ORA-01555 with Export Datapump (文档 ID 1580798.1)

这个错误是很早就publisher的。
主要是说在执行导出或查询某张表的时候，又有其它用户对该表进行了行修改。
修改提交后，通常UNDO中会保留这些旧的资料，用来保证数据一致性读。

如果UNDO保留时间到了，并且UNDO中无足够空间，这些在UNDO中的旧资料就会被覆盖。那些依靠这些数据的操作就无法获得一致性读，从而报错：ORA-01555

建议修改undo_retention、undo tablespace size到合适的大小
或者选择数据库空闲时间段执行expdp作业

ps: 在oracle11g中，EM advice centre - undo advisor 可以评估undo表空间和undo retention如何设置