客戶某套ogg總是莫名丟數，檢查各個配置文件，均配置正確。
查看discard文件和rpt文件發現警告WARNING OGG-00723, OGG-00715，此時可以確定是源端的抽取漏抽數據。
查詢mos發現文章1458472.1有比較清楚的解釋。
Applies to:
Oracle GoldenGate - Version 11.1.1.0.0 and later
Information in this document applies to any platform.
Symptoms
Extract report shows following messages:
2012-03-05 09:14:54 WARNING OGG-00723 Oracle GoldenGate Capture for Oracle, ext_bi.prm: Record with class# 34, slt# 4, at seqno 77324,
rba 32995856 SCN 27.2929925862 (118894042854) has secondary transaction ID that is duplicate of existing open uncommitted transaction.
2012-03-05 09:14:54 WARNING OGG-00715 Oracle GoldenGate Capture for Oracle, ext_bi.prm: [Thread #1] Purging transaction
(transaction id: 9.4.26367119, start time: 2012-03-05 09:11:35, start seqno: 77323, start RBA: 154945040).
2012-03-05 09:14:54 WARNING OGG-00712 Oracle GoldenGate Capture for Oracle, ext_bi.prm: Updating I/O checkpoint after purging
orphaned transactions on thread 1 with current position (Seq#: 77324, RBA: 32998564). s
Cause
1) This is due to the presence of XA (distributed transactions).報錯一致，官方給出的原因也是很明確，XA
This can be verified by running the following query:
下面語句就是測試你的數據庫是否是XA
sql> spool output.txt
set headin off
select /*+ ORDERED */
'-------- Found Global XID -----------------------'||'
Current Time : '|| substr(to_char(sysdate,'dd-Mon-YYYY HH24.MI.SS'),1,22) ||'
'||'Ascii GTXID='||g.K2GTITID_ORA
from x$k2gte g;
set headin off
select /*+ ORDERED */
'----------------------------------------'||'
Curent Time : '|| substr(to_char(sysdate,'dd-Mon-YYYY HH24.MI.SS'),1,22) ||'
'||'GTXID='||substr(g.K2GTITID_EXT,1,10) ||'
'||'Ascii GTXID='||g.K2GTITID_ORA ||'
'||'Branch= '||g.K2GTIBID ||'
Local TX Id ='||substr(t.KXIDUSN||'.'||t.kXIDSLT||'.'||t.kXIDSQN,1,10) ||'
'||'KTUXESTA='|| x.KTUXESTA ||'
'||'KTUXEDFL='|| x.KTUXECFL
from x$k2gte g, x$ktcxb t, X$KTUXE x
where g.K2GTDXCB =t.ktcxbxba and
x.KTUXEUSN = t.KXIDUSN(+) and
x.KTUXESLT = t.kXIDSLT(+) and
x.KTUXESQN =t.kXIDSQN(+);
set headin on
sql> spool off
Extract/ Classic Extract encountered a shutdown of an instance, and is purging any transactions that are open on that instance.
Extract/ Classic Extract does not have the capability to handle XA transactions on RAC. It may purge XA transactions that would eventually
commit. Note the first warning (secondary transaction ID that is duplicate of existing open uncommitted transaction) suggests that we have encountered
XA on RAC.
There can be data loss (precisely in such cases where an instance with an XA branch crashes and the crashed XA txn is recovered in another instance).
2) This can also be caused due to streamlined dblogreader code which was added in OGG version 11.2.1.0.7 and it was disabled in OGG version 11.2.1.0.32
Solution
1) Upgrade to OGG v11.2 and configure "Integrated Extract" which supports XA transactions.
How To Upgrade From Goldengate Classic Extract To Integrated Extract (Doc ID 1484313.1)
For environments using Classic Extract, the following can be used as a work-around
_clusterwide_global_transactions=false
1. What is the impact of setting "_clusterwide_global_transactions"=false
This will ensure that ALL branches of XA goes to the same Oracle instance. However if the instance fails the whole XA transaction will roll back.
This will only impact incoming distributed transactions.
2. For existing connections will it be transparent ?
It is not transparent. We still have to setup services to accept XA connections.
From the Oracle 10.2 doc:
For services that you are going to use for distributed transaction processing, create the service using Enterprise Manager, DBCA, or SRVCTL and
define only one instance as the preferred instance. You can have as many AVAILABLE instances as you want. For example, the following SRVCTL command
creates a singleton service for database crm, xa_01.service.us.oracle.com, whose preferred instance is RAC01:
eg., srvctl add service -d crm -s xa_01.service.us.oracle.com -r RAC01 -a RAC02, RAC03
For incoming transactions we will have to set up the services as explained above. Then mark the service for distributed transaction processing by
setting the DTP parameter to TRUE; the default is FALSE. Enterprise Manager enables you to set this parameter on the Cluster Managed Database Services: Create
Service or Modify Service page. You can also use the DBMS_SERVICE package to modify the DTP property of the singleton service as follows:
eg., EXECUTE DBMS_SERVICE.MODIFY_SERVICE(service_name=>'xa_01.service.us.oracle.com', DTP=>TRUE);
If, for example, RAC01 which provides service XA_01 fails, then the singleton service that it provided fails over to one of the other instances, such as
RAC02 or RAC03.
Additional details on XA transactions are available in following document
http://www.oracle.com/technetwork/products/clustering/overview/distributed-transactions-and-xa-163941.pdf
2) If using OGG versions 11.2.1.0.7 through 11.2.1.0.31 and 12.1.2.0.0 through 12.1.2.1.4 add TRANLOGOPTIONS _DISABLESTREAMLINEDDBLOGREADER to the extract to fix the issue with streamlined
dblogreader code. Starting with OGG versions 11.2.1.0.32 and 12.1.2.1.5 streamlined db logreader is disabled by default.
可以使用腳本驗證spoolout.txt處的腳本，輸入之後，如果有結果就是XA，如果沒有結果（no rows select）就不是XA。--注意要多運行幾次
關於在XA模式下如何保證抽取不丟數，參看mos上的另一篇文章：ogg將普通模式轉換成集成模式