最近两天生产数据库一直在报ORA-24756错误，查了MOS上的文档，看到一篇类似的，说是BUG(Bug 19201866 - RECO reports ORA-24756 repeatedly into trace file (文档 ID 19201866.8))，但是HP-UX上的11.2.0.4没有解决需要升级到12.2版本，文档中还说重启实例也可以解决，但是不现实。
于是查报错时的trace文件都是如下的内容
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*** 2017-02-04 09:17:56.058
ERROR, tran=42.13.2709343, ose=0:
ORA-24756:
......
看到tran=42.13.2709343，印象中是分布式事务，于是查DBA_2PC_PENDINGS视图
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SYS@db1> COL LOCAL_TRAN_ID FORMAT A13
SYS@db1> COL GLOBAL_TRAN_ID FORMAT A90
SYS@db1> COL STATE FORMAT A10
SYS@db1> COL MIXED FORMAT A3
SYS@db1> COL HOST FORMAT A10
SYS@db1> COL COMMIT# FORMAT A15
SYS@db1> SET LINESIZE 240
SYS@db1> SELECT LOCAL_TRAN_ID, GLOBAL_TRAN_ID, STATE,FAIL_TIME,FORCE_TIME,RETRY_TIME, MIXED, HOST, COMMIT#
2 FROM DBA_2PC_PENDING
3 /
LOCAL_TRAN_ID GLOBAL_TRAN_ID STATE FAIL_TIME FORCE_TIME RETRY_TIME MIX HOST COMMIT#
------------- ------------------------------------------------------------------------------------------ ---------- ----------------- ----------------- ----------------- --- ---------- ---------------
42.13.2709343 1096044365.31302E3235352E3233322E32332E746D313438363137313036383638333230333633 collecting 20170204 09:17:55 20170206 01:12:41 no bosbpm4s 764631398601
看到LOCAL_TRAN_ID和trace文件中的tran一致，刚开始的设想是正确的。其中FAIL_TIME是20170204 09:17:55对应到后台的alert日志中，看到这个时间前后的报错信息
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Sat Feb 04 09:17:50 2017
Error 22 trapped in 2PC on transaction 42.13.2709343. Cleaning up.
Error stack returned to user:
ORA-02050: transaction 42.13.2709343 rolled back, some remote DBs may be in-doubt
ORA-00022: invalid session ID; access denied
ORA-02063: preceding line from LINK_DB2
Sat Feb 04 09:17:56 2017
DISTRIB TRAN 41544f4d.31302E3235352E3233322E32332E746D313438363137313036383638333230333633
is local tran 42.13.2709343 (hex=2a.0d.29575f)
insert pending collecting tran, scn=764631398601 (hex=b2.079538c9)
Sat Feb 04 09:17:56 2017
Errors in file /Oracle11g/app/oracle/diag/rdbms/db1/db1/trace/db1_reco_23402.trc:
ORA-24756:
这种分布式事务故障可能会锁定数据导致其他事务报ORA-01591报错或者一直占用UNDO段不能被别的事务重用。需要手工处理这种故障。
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SYS@db1> EXECUTE DBMS_TRANSACTION.PURGE_LOST_DB_ENTRY('42.13.2709343');
PL/SQL procedure successfully completed.
SYS@db1> commit;
Commit complete.
SYS@db1> SELECT LOCAL_TRAN_ID, GLOBAL_TRAN_ID, STATE,FAIL_TIME,FORCE_TIME,RETRY_TIME, MIXED, HOST, COMMIT#
2 FROM DBA_2PC_PENDING
3 /
no rows selected
清理完毕。
管理分布式事务的官方文档：http://docs.oracle.com/cd/E11882_01/server.112/e25494/ds_txnman.htm#ADMIN12252
MOS文档：How to Purge a Distributed Transaction from a Database (文档 ID 159377.1) ORA-30019 When Executing Dbms_transaction.Purge_lost_db_entry (文档 ID 290405.1)
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