今天用expdp导数据出现ORA-01555: snapshot too old 错误，表中有clob字段，增加retention time和增加undo表空间都没有用，最后发现是有LOB segment corruption。
ORA-31693: Table data object "NEWCMS"."ARTICLE" 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 with name "" too small
ORA-22924: snapshot too old
create table corrupted_data (corrupted_rowid rowid);
检查坏块
set concat off
declare
error_1555 exception;
pragma exception_init(error_1555,-1555);
v_lob NCLOB;
n number;
begin
for cursor_lob in (select rowid r from article.html_context) loop
begin
select PT_DESC into v_lob from article.html_context where rowid=cursor_lob.r;
n:=dbms_lob.instr(v_lob,hextoraw('889911')) ;
exception
when error_1555 then
insert into corrupted_data values (cursor_lob.r);
commit;
end;
end loop;
end;
/
PL/sql procedure successfully completed.
sql> select * from corrupted_data;
CORRUPTED_ROWID
------------------
AAAS6HAAKAAB++3AAA
发现有一条数据损坏
导出时过滤掉该条记录
expdp newcms/********* schemas=newcms dumpfile=newcms_20160509.dmp query=\"where rowid not in \(\'AAAS6HAAKAAB++3AAA\'\)\" version=10.2.0.4.0
成功导出
在导入时报错
ORA-39083: Object type REF_CONSTRAINT Failed to create with error:
ORA-02298: cannot validate (NEWCMS.FK_ARTICLE__REFERENCE_ARTICLE) - parent keys not found
Failing sql is:
ALTER TABLE "NEWCMS"."ARTICLE_TO_COLUMN" ADD CONSTRAINT "FK_ARTICLE__REFERENCE_ARTICLE" FOREIGN KEY ("ARTICLE_CODE") REFERENCES "NEWCMS"."ARTICLE" ("ID") ENABLE
Processing object type SCHEMA_EXPORT/TABLE/STATISTICS/TABLE_STATISTICS
Job "NEWCMS"."SYS_IMPORT_FULL_01" completed with 2 error(s) at 14:45:36
原因:
你要插入的表A里，有外键连接到另一个表B的主键， 你在表A的外键列插入的值 在表B的主键列找不到就不能插入。
解决方法:
如果可以删除主表中的多余记录，保证主表和子表一致
SELECT ' delete from '
||a.table_name
||' a where not exists ( select 1 from '
||c_pk.table_name
|| ' b where b.'
|| b.column_name
||'=a.'
||a.column_name
||');'
FROM user_cons_columns a
JOIN user_constraints c
ON a.constraint_name = c.constraint_name
JOIN user_constraints c_pk
ON c.r_constraint_name = c_pk.constraint_name
JOIN user_cons_columns b
ON c_pk.constraint_name = b.constraint_name
WHERE c.constraint_type = 'R'
AND a.table_name = '&Table_Name'
AND a.constraint_name ='&FK_NAME';
'DELETEFROM'||A.TABLE_NAME||'AWHERENOTEXISTS(SELECT1FROM'||C_PK.TABLE_NAME||'BWH
--------------------------------------------------------------------------------
delete from ARTICLE_TO_COLUMN a where not exists ( select 1 from ARTICLE b wh
ere b.ID=a.ARTICLE_CODE);
执行该语句
然后执行
alter table "ARTICLE_TO_COLUMN" enable constraint "FK_ARTICLE__REFERENCE_ARTICLE";
成功！
