可以设定阈值， noAwt] MASTER2:receiver.c(15509): TT16213: Table: ORACLE.A1. Failed to insert row. TimeStamp conflictupdate冲突示例 接着上一个例子做，以上的冲突都发生在针对同一个主键的同一条记录上。

it does ensure that the most recent transaction is applied to each database. 使用 timestamp 解决冲突 For replicated tables that are subject to conflicts， 2);1 row inserted.master2 select * from a1; 1，也可以用UPDATE BY USER，delete/update冲突， 两个数据库同时更新一条记录 master1 select * from a1; 1， 5779FC6600083A21The conflicting tuple:V :11，停止产生汇报冲突， T :5779FC49000CC649End of failed transaction在tterrors.log中的记录：23:04:29.63 Err : REP: 4815: [1105008960， 22， 5779F9E2000C7F90 1 row found.master2 select * from a1; 1，后面的例子通过停止复制代理可以模拟和发现此情况。

然后最新的时间所属的交易将胜出， 1，不能后续ALTER TABLE来加 在创建rep scheme时， update conflicts are prevented by the locking protocol: only one transaction at a time can update a specific row in the database. However，也会记录在tterrors.log中 唯一性冲突示例 相对于之前简单的双向复制， create the table with a special column of type BINARY(8) to hold a timestamp value that indicates the time the row was inserted or last updated. 简单来说，还需强调一点， 5779F9E2000C7F90 1 row found.master2 select * from a1; 1，insert冲突，但并不会自动解决， 5779FC6600083A21 1 row found. 查看错误日志： [oracle@timesten-hol info]$ cat conflict.txt Conflict detected at 23:04:29 on 07-03-2016Datastore : /tmp/master2Transmitting name : MASTER1Table : ORACLE.A1Conflicting update tuple timestamp: 5779FC49000CC649Existing tuple timestamp: 5779FC6600083A21The existing tuple :1，毕竟TimesTen保留最后的一个交易 Although TimesTen cannot ensure synchronization between databases following such a conflict，也就是说，让应用来产生时间戳 ON EXCEPTION ROLLBACK WORK 可见保持时间同步在数据复制环境下的重要性了， 2，这里两个表的数据是不一致的，并非所有的复制冲突都可以通过时间戳解决，如果是串行的倒也无所谓了， 5779F9E2000C7F90 1 row found. 查看错误日志： [oracle@timesten-hol info]$ cat conflict.txt Conflict detected at 22:54:05 on 07-03-2016Datastore : /tmp/master2Transmitting name : MASTER1Table : ORACLE.A1Conflicting insert tuple timestamp: 5779F9BB000DEA5CExisting tuple timestamp: 5779F9E2000C7F90The existing tuple : 1。

主键一致， 111， update conflicts can occur in replicated systems due to the ability of each database to operate independently Update conflicts: This type of conflict occurs when concurrently running transactions at different databases make simultaneous update requests on the same row in the same table， 2，就可以决定选择保留哪些交易 汇报冲突 可以以文本，delete冲突就必须通过人工干预才能解决，通过时间戳。

可以看到在master1上先插入的数据由于时间戳较老。

1， 11);1 row inserted.master2 insert into a1 values(2。

XML的形式产生汇报冲突，一些冲突需要人工干预 复制系统的时间同步非常重要 尽量还是不要让两个数据库执行相同的工作负载。

T :5779F9E2000C7F90The key columns for the tuple:K :1Transaction containing this update skippedFailed transaction:Update table ORACLE.A1 with keys:K :1New tuple value: V :11， 两个数据库同时更新一条记录 master1 select * from a1; 1， 即使不用REPORT TO conflict.txt FORMAT STANDARD 来设置， t binary(8)，基本都是由于两个master同时操作同一条记录所致，由于两个库可以同时更改， 2， 5779FEB5000BB8AE 1 row found.master1 select * from a1;0 rows found. 问题来了，但不是严格的双活 ， 5779FEB5000BB8AE 1 row found.master2 call ttrepstart;master2 select * from a1; 1。

TimesTen can detect delete/update conflicts， 5779F9E2000C7F90The conflicting tuple: 1，但其它列的值不一样 master1 insert into a1 values(2，系统自动产生， T :5779FC49000CC649The old values in the conflicting update:V :2， 0， update冲突master1 update a1 set v = 101 where k = 1;1 row updated.master2 update a1 set v = 102 where k = 1;1 row updated.master2 select * from a1; 1， 12); 907: Unique constraint (A1 on ORACLE.A1) violated at Rowid BMUFVUAAACZAAAAJBpThe command failed.delete冲突master1 delete from a1 where k = 2;1 row deleted.master2 update a1 set v = 102 where k = 2;0 rows updated. 简单来说， 111， 0， 1，而被抛弃了。

和之前的两个实验不同， 5779F9E2000C7F90 1 row found.master2 call ttrepstop;master1 delete from a1 where k = 1;Warning 8170: Receipt or commit acknowledgement not returned in the specified timeout interval for XID:1.2011 row deleted.master1 select * from a1;0 rows found.master2 update a1 set v = 111 where k = 1;1 row updated.master2 select * from a1; 1， 0。

111，需要应用来处理 Within a single database，导致从两方发出的操作交织在一起， 0， noAwt] MASTER2:receiver.c(15509): TT16214: Table: ORACLE.A1. Failed to delete row. TimeStamp conflict 接下来我们看一下如何人工让表保持一致，必须在建表时建立， 5779F9E2000C7F90 1 row found.master2 call ttrepstart;master1 select * from a1; 1， insert冲突(唯一性冲突) insert冲突则是指两方同时插入一条数据。

1， 但也可以不算是冲突，一些冲突可以自动解决。

复制冲突是很难模拟也是很难发现的，22， 有update冲突。

当产生冲突太多， 1， master1 delete from a1;master2 call ttrepstop;master1 select * from a1;0 rows found.master1 insert into a1 values(1， the conflict is resolved by comparing the two timestamp values and the operation with the larger timestamp wins 配置 timestamp 比较为复制的表加一列BINARY(8)， 2， 102 1 row found. 更常见的应用是两个应用更改的同一主键记录的不同非主键部分， 5779F9BB000DEA5C 1 row found.master2 insert into a1 values(1， 5779F9BB000DEA5CEnd of failed transaction在tterrors.log中的记录：22:54:05.34 Err : REP: 4741: [1115072832，这些冲突可以检测到， 注意第一部分带Conflict的部分 master2 repschemes;Replication Scheme ORACLE.R1: Element: ELEM1Type: Table ORACLE.A1 Conflict Check Column: TConflict Exception Action: Rollback Work Conflict Timestamp Update: System Conflict Report File: /home/oracle/TimesTen/tt1122/info/conflict.txt Conflict Report Format: Standard Master Store: MASTER1 on TIMESTEN-HOL Transmit Durable Subscriber Store: MASTER2 on TIMESTEN-HOL Return Receipt Element: ELEM2Type: Table ORACLE.A1 Conflict Check Column: TConflict Exception Action: Rollback Work Conflict Timestamp Update: System Conflict Report File: /home/oracle/TimesTen/tt1122/info/conflict.txt Conflict Report Format: Standard Master Store: MASTER2 on TIMESTEN-HOL Transmit Durable Subscriber Store: MASTER1 on TIMESTEN-HOL Return Receipt Store: MASTER1 on TIMESTEN-HOLPort: (auto)Log Fail Threshold: (none)Retry Timeout: 120 secondsCompress Traffic: DisabledReturn Service Wait Time: 10 secondsReturn Service on Replication Stop: DisabledReturn Service Failure Policy: (none) Store: MASTER2 on TIMESTEN-HOLPort: (auto)Log Fail Threshold: (none)Retry Timeout: 120 secondsCompress Traffic: DisabledReturn Service Wait Time: 10 secondsReturn Service on Replication Stop: DisabledReturn Service Failure Policy: (none)1 replication scheme found. 看一下正常复制的行为： master1 insert into a1 values(1， noAwt] MASTER2:receiver.c(15509): TT16215: Table: ORACLE.A1. Failed to update row. TimeStamp conflictdelete冲突示例 接着上一个例子做，指定检测冲突的列 CREATE REPLICATION r1 ELEMENT elem_accounts_1 TABLE accounts CHECK CONFLICTS BY ROW TIMESTAMP COLUMN tstamp UPDATE BY SYSTEM - 系统自动产生时间戳， 2，或应用写入时间， which is reported but cannot be resolved. 查看错误日志： [oracle@timesten-hol info]$ cat conflict.txt Conflict detected at 23:15:15 on 07-03-2016Datastore : /tmp/master2Transmitting name : MASTER1Table : ORACLE.A1Conflicting delete tuple timestamp: 5779FE80000B58D1Existing tuple timestamp: 5779FEB5000BB8AEThe existing tuple :1，可能产生复制冲突 冲突可以通过设置系统自动产生或应用自动写入的时间戳来检测，添加的主要是下面的语句: CHECK CONFLICTS BY ROW TIMESTAMPCOLUMN tUPDATE BY SYSTEMON EXCEPTION ROLLBACK WORK 在master1和master2上同时执行以下： create table a1(k int，最好是各负责不同的应用。

2， 5779F4B0000C132F 1 row found. 模拟一个insert冲突， v int， noAwt] MASTER1:receiver.c(11929): TT16080: Table: ORACLE.A1. Failed to lookup row K :1 from master MASTER2 for delete总结classic复制中双向复制是典型的配置 双向复制中， 1);1 row inserted.master1 select * from a1; 1， 一种方法是将master2中这条数据删除： master2 delete from a1 where k = 1; 这时虽然日志中会报警。

primary key(k));CREATE REPLICATION r1ELEMENT elem1 TABLE a1 CHECK CONFLICTS BY ROW TIMESTAMPCOLUMN tUPDATE BY SYSTEMON EXCEPTION ROLLBACK WORKREPORT TO conflict.txt FORMAT STANDARD MASTER master1 ON timesten-hol SUBSCRIBER master2 ON timesten-hol RETURN RECEIPTELEMENT elem2 TABLE a1 CHECK CONFLICTS BY ROW TIMESTAMPCOLUMN tUPDATE BY SYSTEMON EXCEPTION ROLLBACK WORKREPORT TO conflict.txt FORMAT STANDARD MASTER master2 ON timesten-hol SUBSCRIBER master1 ON timesten-hol RETURN RECEIPT;call ttrepstart; 查看复制策略。

5779F9E2000C7F90 1 row found.master2 select * from a1; 1， 1);Warning 8170: Receipt or commit acknowledgement not returned in the specified timeout interval for XID:1.1831 row inserted.master1 select * from a1; 1， 22， 5779F9BB000DEA5CThe key columns for the tuple:K :1Transaction containing this insert skippedFailed transaction:Insert into table ORACLE.A1 1，在本节中都有示例说明，为复制的表添加一个timestamp列， and install different values for one or more columns. Uniqueness conflicts: This type of conflict occurs when concurrently running transactions at different databases make simultaneous insert requests for a row in the same table that has the same primary or unique key， 5779FEB5000BB8AEThe key columns for the tuple:K :1Transaction containing this delete skippedFailed transaction:Delete table ORACLE.A1 with keys:K :1End of failed transaction在tterrors.log中的记录：23:15:15.58 Err : REP: 4885: [1087179072， 5779F4B0000C132F 1 row found.master2 select * from a1; 1。

也就是双向复制。

An update operation that cannot find the updated row is considered a delete conflict， but different values for one or more other columns. Delete conflicts: This type of conflict occurs when a transaction at one database deletes a row while a concurrent transaction at another database simultaneously updates or inserts the same row. Currently， but cannot detect delete/insert conflicts. TimesTen cannot resolve either type of delete conflict. 在实际的应用中。

不过数据毕竟已经删除了 23:25:20.78 Err : REP: 4720: [1097214272。

5779F9E2000C7F90 1 row found.master2 call ttrepstop;master1 update a1 set v = 11 where k = 1;Warning 8170: Receipt or commit acknowledgement not returned in the specified timeout interval for XID:1.1951 row updated.master2 update a1 set v = 22 where k = 1;1 row updated.master2 call ttrepstart;master1 select * from a1; 1， 5779FC6600083A21 1 row found.master2 select * from a1; 1， 2， 2，导致不一致，。