EXPDP导出带LOB字段表报ORA-01555错误解决-CFANZ编程社区

问题概述

expdp导出数据，结果遇到如下报错：

Processing object type DATABASE_EXPORT/SCHEMA/POST_SCHEMA/PROCACT_SCHEMA
ORA-31693: Table data object "USER1"."TKINFO" failed to load/unload and is being skipped due to error:
ORA-29913: error in executing ODCIEXTTABLEPOPULATE callout
ORA-01555: snapshot too old: rollback segment number with name "" too small
ORA-22924: snapshot too old

问题原因

遇到ORA-01555报错最直接的反应就是undo表空间大小是否足够，undo_retention参数是否设置太小。经过验证，均不是以上问题造成的。由于该表格有BLOB类型的列，怀疑BLOB有损坏。

解决方案

1、开始排查是否有LOB字段的行存在损坏：

SQL> create table corrupted_lob_data (corrupt_rowid rowid, err_num number);

2、执行如下plsql块，找出存在损坏lob的行：

declare
error_1578 exception;
error_1555 exception;
error_22922 exception;
pragma exception_init(error_1578,-1578);
pragma exception_init(error_1555,-1555);
pragma exception_init(error_22922,-22922);
n number;
begin
  for cursor_lob in (select rowid r, &&lob_column from &table_owner..&table_with_lob) loop
    begin
      n := dbms_lob.instr (cursor_lob.&&lob_column, hextoraw ('889911')) ;
exception
when error_1578 then
insert into corrupted_lob_data values (cursor_lob.r, 1578);
commit;
when error_1555 then
insert into corrupted_lob_data values (cursor_lob.r, 1555);
commit;
when error_22922 then
insert into corrupted_lob_data values (cursor_lob.r, 22922);
commit;
end;
end loop;
end;
/

Enter value for lob_column: BYTE_IMAGE
Enter value for table_owner: USER1
Enter value for table_with_lob: TKINFO
old 10: for cursor_lob in (select rowid r, &&lob_column from &table_owner..&table_with_lob) loop
new 10: for cursor_lob in (select rowid r, BYTE_IMAGE from USER1.TKINFO) loop
old 12: num := dbms_lob.instr (cursor_lob.&&lob_column, hextoraw ('889911')) ;
new 12: num := dbms_lob.instr (cursor_lob.BYTE_IMAGE, hextoraw ('889911')) ;

3、查询结果发现rowid为AAAhS4AAUAAE3IRAAC的行 blob列有损坏

SQL> select * from corrupt_lobs;

CORRUPT_ROWID ERR_NUM
------------------ ----------
AAAhS4AAUAAE3IRAAC 1555

解决办法:修改导出语句，跳过blob损坏的行，重新expdp，成功导出

expdp user1/XXXXXXXX directory=szdata1 dumpfile=szhzinfo_20180319.dmp logfile=szhzinfo_20180319.log exclude=STATISTICS,INDEX tables=TKINFO QUERY=\"WHERE rowid NOT IN \(\'AAAhS4AAUAAE3IRAAC\'\)\"

修复坏块

--如果更新的表的字段类型为CLOB,则用以下脚本修复：
SQL> update 表名 set LOB字段名=empty_clob() where rowid in (select corrupt_rowid from corrupt_lobs);
--如果更新的表的字段类型为BLOB,则用以下脚本修复：
SQL> update 表名 set LOB字段名=empty_blob() where rowid in (select corrupt_rowid from corrupt_lobs);

参考文档

IF: ORA-1555 Error During Export on LOB Data (文档 ID 1950937.1)
LOBs and ORA-01555 troubleshooting (文档 ID 846079.1)