您可以配置Oracle GoldenGate来自动检测和解决在不同站点同时更新相同数据时发生的冲突。
Topics:
当Oracle GoldenGate复制Oracle数据库之间的更改时,您可以在这些数据库中配置和管理Oracle GoldenGate自动冲突检测和解决。为此,必须确保PL/SQL调用在源和目标数据库上执行。此功能用于双向复制。
Note:
本章针对在Oracle数据库中配置的Oracle GoldenGate 12c(12.3.0.1)和Oracle数据库12c Release 2(12.2)及其后版本的自动冲突检测和解决特性。还有一个用于冲突检测和解决的通用Oracle GoldenGate特性,称为Oracle GoldenGate冲突检测和解决(CDR)。Oracle GoldenGate CDR是在Replicat参数文件中配置的。
You can configure only one of the following types of automatic conflict detection and resolution for a single table:
The automatic conflict detection and resolution feature that is specific to Oracle Database 12c Release 2 (12.2)
Oracle GoldenGate CDR
Parent topic: Automatic Conflict Detection and Resolution
您可以在Oracle GoldenGate配置中配置自动冲突检测和解决,该配置在Oracle数据库之间复制表。要配置表的冲突检测和解决,请调用DBMS_GOLDENGATE_ADM包中的ADD_AUTO_CDR过程。
Oracle GoldenGate捕获源自Oracle数据库的更改时,每个更改都封装在一个行逻辑更改记录(LCR)中。行LCR是DML行更改的结构化表示。每行LCR包括操作类型、旧列值和新列值。多行LCRs可以是单个数据库事务的一部分。
When more than one replica of a table allows changes to the table, a conflict can occur when a change is made to the same row in two different databases at nearly the same time. Oracle GoldenGate replicates changes using the row LCRs. It detects a conflict by comparing the old values in the row LCR for the initial change from the origin database with the current values of the corresponding table row at the destination database identified by the key columns. If any column value does not match, then there is a conflict.
After a conflict is detected, Oracle GoldenGate can resolve the conflict by overwriting values in the row with some values from the row LCR, ignoring the values in the row LCR, or computing a delta to update the row values.
Automatic conflict detection and resolution does not require application changes for the following reasons:
Oracle Database automatically creates and maintains invisible timestamp columns.
Inserts, updates, and deletes use the delete tombstone log table to determine if a row was deleted.
LOB column conflicts can be detected.
Oracle Database automatically configures supplemental logging on required columns.
Note:
If you use the classic Replicat on tables that have Automatic Change Detection and Resolution enabled, the Extract might abend with the OGG-10461 Failed to retrieve timestamp error. This is because the internal trigger that inserts the records into tombstone tables, only fires on user DMLs. A classic Replicat suppresses all the triggers from firing, which results in missing inserts on tombstone tables.
Supplemental logging is required to ensure that each row LCR has the information required to detect and resolve a conflict. Supplemental logging places additional information in the redo log for the columns of a table when a DML operation is performed on the table. When you configure a table for Oracle GoldenGate conflict detection and resolution, supplemental logging is configured automatically for all of the columns in the table. The additional information in the redo log is placed in an LCR when a table change is replicated.
See Also:
Oracle Database Utilities for information about supplemental logging
Parent topic: About Automatic Conflict Detection and Resolution
当您在DBMS_GOLDENGATE_ADM包中运行ADD_AUTO_CDR过程来配置用于自动Oracle GoldenGate冲突检测和解决的表时,将向表中添加一个隐藏的时间戳列。这个隐藏的时间戳列记录行更改的时间,该信息用于检测和解决冲突。
When a row LCR is applied, a conflict can occur for an INSERT
, UPDATE
, or DELETE
operation. The following table describes each type of conflict and how it is resolved.
Operation | Conflict Detection | Conflict Resolution |
---|---|---|
|
A conflict is detected when the table has the same value for a key column as the new value in the row LCR. |
If the timestamp of the row LCR is later than the timestamp in the table row, then the values in the row LCR replace the values in the table. If the timestamp of the row LCR is earlier than the timestamp in the table row, then the row LCR is discarded, and the table values are retained. |
|
A conflict is detected in each of the following cases:
|
If there is a value mismatch and the timestamp of the row LCR is later than the timestamp in the table row, then the values in the row LCR replace the values in the table. If there is a value mismatch and the timestamp of the row LCR is earlier than the timestamp in the table row, then the row LCR is discarded, and the table values are retained. If the table row does not exist and the timestamp of the row LCR is later than the timestamp in the tombstone table row, then the row LCR is converted from an If the table row does not exist and the timestamp of the row LCR is earlier than the timestamp in the tombstone table row, then the row LCR is discarded. If the table row does not exist and there is no corresponding row in the tombstone table, then the row LCR is converted from an |
|
A conflict is detected in each of the following cases:
|
If the timestamp of the row LCR is later than the timestamp in the table, then delete the row from the table. If the timestamp of the row LCR is earlier than the timestamp in the table, then the row LCR is discarded, and the table values are retained. If the delete is successful, then log the row LCR by inserting it into the tombstone table. If the table row does not exist, then log the row LCR by inserting it into the tombstone table. |
Parent topic: About Automatic Conflict Detection and Resolution
使用delta冲突检测,当行LCR的旧列列表中的值与表中相应行的值不同时,就会发生冲突。
To configure delta conflict detection and resolution for a table, run the ADD_AUTO_CDR_DELTA_RES
procedure in the DBMS_GOLDENGATE_ADM
package. The delta resolution method does not depend on a timestamp or an extra resolution column. With delta conflict resolution, the conflict is resolved by adding the difference between the new and old values in the row LCR to the value in the table. This resolution method is generally used for financial data such as an account balance. For example, if a bank balance is updated at two sites concurrently, then the converged value accounts for all debits and credits.
Description of the illustration xstrm_3v_086a.png
This example shows a row being replicated at database A and database B. The Balance
column is designated as the column on which delta conflict resolution is performed, and the TS1
column is the invisible timestamp column to track the time of each change to the Balance
column. A change is made to the Balance
value in the row in both databases at nearly the same time (@T20
in database A and @T22
in database B). These changes result in a conflict, and delta conflict resolution is used to resolve the conflict in the following way:
At database A, the value of Balance
was changed from 100
to 110
. Therefore, the value was increased by 10.
At database B, the value of Balance
was changed from 100
to 120
. Therefore, the value was increased by 20.
To resolve the conflict at database A, the value of the difference between the new and old values in the row LCR to the value in the table. The difference between the new and old values in the LCR is 20 (120–100=20). Therefore, the current value in the table (110) is increased by 20 so that the value after conflict resolution is 130.
To resolve the conflict at database B, the value of the difference between the new and old values in the row LCR to the value in the table. The difference between the new and old values in the LCR is 10 (110–100=10). Therefore, the current value in the table (120) is increased by 10 so that the value after conflict resolution is 130.
After delta conflict resolution, the value of the Balance
column is the same for the row at database A and database B.
Parent topic: About Automatic Conflict Detection and Resolution
A column group is a logical grouping of one or more columns in a replicated table. When you add a column group, conflict detection and resolution is performed on the columns in the column group separately from the other columns in the table.
When you configure a table for Oracle GoldenGate conflict detection and resolution with the ADD_AUTO_CDR
procedure, all of the scalar columns in the table are added to a default column group. To define other column groups for the table, run the ADD_AUTO_CDR_COLUMN_GROUP
procedure. Any columns in the table that are not part of a user-defined column group remain in the default column group for the table.
Column groups enable different databases to update different columns in the same row at nearly the same time without causing a conflict. When column groups are configured for a table, conflicts can be avoided even if different databases update the same row in the table. A conflict is not detected if the updates change the values of columns in different column groups.
Description of the illustration xstrm_3v_086a.png
This example shows a row being replicated at database A and database B. The following two column groups are configured for the replicated table at each database:
One column group includes the Office
column. The invisible timestamp column for this column group is TS1
.
Another column group includes the Title
and Salary
columns. The invisible timestamp column for this column group is TS2
.
These column groups enable database A and database B to update the same row at nearly the same time without causing a conflict. Specifically, the following changes are made:
At database A, the value of Office
was changed from 1080
to 1030
.
At database B, the value of Title
was changed from MTS1
to MTS2
.
Because the Office
column and the Title
column are in different column groups, the changes are replicated without a conflict being detected. The result is that values in the row are same at both databases after each change has been replicated.
Piecewise LOB Updates
A set of lob operations composed of LOB WRITE
, LOB ERASE
, and LOB TRIM
is a piecewise LOB update. When a table that contains LOB columns is configured for conflict detection and resolution, each LOB column is placed in its own column group, and the column group has its own hidden timestamp column. The timestamp column is updated on the first piecewise LOB operation.
For a LOB column, a conflict is detected and resolved in the following ways:
If the timestamp for the LOB’s column group is later than the corresponding LOB column group in the row, then the piecewise LOB update is applied.
If the timestamp for the LOB’s column group is earlier than the corresponding LOB column group in the row, then the LOB in the table row is retained.
If the row does not exist in the table, then an error occurs
Parent topic: About Automatic Conflict Detection and Resolution
You can configure Oracle GoldenGate automatic conflict detection and resolution in Oracle Database with the DBMS_GOLDENGATE_ADM
package.
For the Replicat parameter file you need to add a MAP
statement that includes the table to be replicated and the MAPINVISIBLECOLUMNS
parameter.
Parent topic: Automatic Conflict Detection and Resolution
DBMS_GOLDENGATE_ADM包中的ADD_AUTO_CDR过程配置最新的时间戳冲突检测和解决。ADD_AUTO_CDR_COLUMN_GROUP过程添加可选的列组。
With latest timestamp conflict detection and resolution, a conflict is detected when the timestamp column of the row LCR does not match the timestamp of the corresponding table row. The row LCR is applied if its timestamp is later. Otherwise, the row LCR is discarded, and the table row is not changed. When you run the ADD_AUTO_CDR
procedure, it adds an invisible timestamp column for each row in the specified table and configures timestamp conflict detection and resolution. When you use the ADD_AUTO_CDR_COLUMN_GROUP
procedure to add one or more column groups, it adds a timestamp for the column group and configures timestamp conflict detection and resolution for the column group.
You can configure an Oracle GoldenGate administrator using the GRANT_ADMIN_PRIVILEGE
procedure in the DBMS_GOLDENGATE_ADM
package.
ADD_AUTO_CDR
procedure and specify the table to configure for latest timestamp conflict detection and resolution.ADD_AUTO_CDR_COLUMN_GROUP
procedure and specify one or more column groups in the table.Example 16-1 Configuring the Latest Timestamp Conflict Detection and Resolution for a Table
This example configures latest timestamp conflict detection and resolution for the hr.employees
table.
BEGIN
DBMS_GOLDENGATE_ADM.ADD_AUTO_CDR(
schema_name => 'hr',
table_name => 'employees');
END;
/
Example 16-2 Configuring Column Groups
This example configures the following column groups for timestamp conflict resolution on the hr.employees
table:
The job_identifier_cg
column group includes the job_id
, department_id
, and manager_id
columns.
The compensation_cg
column group includes the salary
and commission_pct
columns.
BEGIN
DBMS_GOLDENGATE_ADM.ADD_AUTO_CDR_COLUMN_GROUP(
schema_name => 'hr',
table_name => 'employees',
column_list => 'job_id,department_id,manager_id',
column_group_name => 'job_identifier_cg');
END;
/
BEGIN
DBMS_GOLDENGATE_ADM.ADD_AUTO_CDR_COLUMN_GROUP(
schema_name => 'hr',
table_name => 'employees',
column_list => 'salary,commission_pct',
column_group_name => 'compensation_cg');
END;
/
Parent topic: Configuring Automatic Conflict Detection and Resolution
DBMS_GOLDENGATE_ADM包中的ADD_AUTO_CDR_DELTA_RES过程配置delta冲突检测和解决。
With delta conflict resolution, you specify one column for which conflicts are detected and resolved. The conflict is detected if the value of the column in the row LCR does not match the corresponding value in the table. The conflict is resolved by adding the difference between the new and old values in the row LCR to the value in the table.
You can configure an Oracle GoldenGate administrator using the GRANT_ADMIN_PRIVILEGE
procedure in the DBMS_GOLDENGATE_ADM
package.
ADD_AUTO_CDR
procedure and specify the table to configure for latest timestamp conflict detection and resolution.ADD_AUTO_CDR_DELTA_RES
procedure and specify the column on which delta conflict detection and resolution is performed.Example 16-3 Configuring Delta Conflict Detection and Resolution for a Table
This example configures delta conflict detection and resolution for the order_total
column in the oe.orders
table.
BEGIN
DBMS_GOLDENGATE_ADM.ADD_AUTO_CDR(
schema_name => 'oe',
table_name => 'orders');
END;
/
BEGIN
DBMS_GOLDENGATE_ADM.ADD_AUTO_CDR_DELTA_RES(
schema_name => 'oe',
table_name => 'orders',
column_name => 'order_total');
END;
/
Parent topic: Configuring Automatic Conflict Detection and Resolution
You can manage Oracle GoldenGate automatic conflict detection and resolution in Oracle Database with the DBMS_GOLDENGATE_ADM
package.
Parent topic: Automatic Conflict Detection and Resolution
The ALTER_AUTO_CDR
procedure in the DBMS_GOLDENGATE_ADM
package alters conflict detection and resolution for a table.
Oracle GoldenGate automatic conflict detection and resolution must be configured for the table:
ALTER_AUTO_CDR
procedure and specify the table to configure for latest timestamp conflict detection and resolution.Example 16-4 Altering Conflict Detection and Resolution for a Table
This example alters conflict detection and resolution for the hr.employees
table to specify that delete conflicts are tracked in a tombstone table.
BEGIN
DBMS_GOLDENGATE_ADM.ALTER_AUTO_CDR(
schema_name => 'hr',
table_name => 'employees',
tombstone_deletes => TRUE);
END;
/
Parent topic: Managing Automatic Conflict Detection and Resolution
The ALTER_AUTO_CDR_COLUMN_GROUP
procedure alters a column group.
ALTER_AUTO_CDR_COLUMN_GROUP
procedure and specify one or more column groups in the table.Example 16-5 Altering a Column Group
This example removes the manager_id
column from the job_identifier_cg
column group for the hr.employees
table.
BEGIN
DBMS_GOLDENGATE_ADM.ALTER_AUTO_CDR_COLUMN_GROUP(
schema_name => 'hr',
table_name => 'employees',
column_group_name => 'job_identifier_cg',
remove_column_list => 'manager_id');
END;
/
Note:
If there is more than one column, then use a comma-separated list.
Parent topic: Managing Automatic Conflict Detection and Resolution
The PURGE_TOMBSTONES
procedure removes tombstone rows that were recorded before a specified date and time. This procedure removes the tombstone rows for all tables configured for conflict resolution in the database.
It might be necessary to purge tombstone rows periodically to keep the tombstone log from growing too large over time.
PURGE_TOMBSTONES
procedure and specify the date and time.Example 16-6 Purging Tombstone Rows
This example purges all tombstone rows recorded before 3:00 p.m. on December, 1, 2015 Eastern Standard Time. The timestamp must be entered in TIMESTAMP WITH TIME ZONE
format.
EXEC DBMS_GOLDENGATE_ADM.PURGE_TOMBSTONES('2015-12-01 15:00:00.000000 EST');
Parent topic: Managing Automatic Conflict Detection and Resolution
The REMOVE_AUTO_CDR
procedure in the DBMS_GOLDENGATE_ADM
package removes automatic conflict detection and resolution from a table. This procedure also removes any column groups and delta conflict detection and resolution configured for the table.
REMOVE_AUTO_CDR
procedure and specify the table.Example 16-7 Removing Conflict Detection and Resolution for a Table
This example removes conflict detection and resolution for the hr.employees
table.
BEGIN
DBMS_GOLDENGATE_ADM.REMOVE_AUTO_CDR(
schema_name => 'hr',
table_name => 'employees');
END;
/
Parent topic: Managing Automatic Conflict Detection and Resolution
The REMOVE_AUTO_CDR_COLUMN_GROUP
procedure removes a column group.
REMOVE_AUTO_CDR_COLUMN_GROUP
procedure and specify the name of the column group.Example 16-8 Removing a Column Group
This example removes the compensation_cg
column group from the hr.employees
table.
BEGIN
DBMS_GOLDENGATE_ADM.REMOVE_AUTO_CDR_COLUMN_GROUP(
schema_name => 'hr',
table_name => 'employees',
column_group_name => 'compensation_cg');
END;
/
Parent topic: Managing Automatic Conflict Detection and Resolution
The REMOVE_AUTO_CDR_DELTA_RES
procedure in the DBMS_GOLDENGATE_ADM
package removes delta conflict detection and resolution for a column.
Delta conflict detection and resolution must be configured for the specified column.
REMOVE_AUTO_CDR_DELTA_RES
procedure and specify the column.Example 16-9 Removing Delta Conflict Detection and Resolution for a Table
This example removes delta conflict detection and resolution for the order_total
column in the oe.orders
table.
BEGIN
DBMS_GOLDENGATE_ADM.REMOVE_AUTO_CDR_DELTA_RES(
schema_name => 'oe',
table_name => 'orders',
column_name => 'order_total');
END;
/
Parent topic: Managing Automatic Conflict Detection and Resolution
You can monitor Oracle GoldenGate automatic conflict detection and resolution in an Oracle Database by querying data dictionary views.
Parent topic: Automatic Conflict Detection and Resolution
The ALL_GG_AUTO_CDR_TABLES
view displays information about the tables configured for Oracle GoldenGate automatic conflict detection and resolution.
ALL_GG_AUTO_CDR_TABLES
view.Example 16-10 Displaying Information About the Tables Configured for Conflict Detection and Resolution
This query displays the following information about the tables that are configured for conflict detection and resolution:
The table owner for each table.
The table name for each table.
The tombstone table used to store rows deleted for update-delete conflicts, if a tombstone table is configured for the table.
The hidden timestamp column used for conflict resolution for each table.
COLUMN TABLE_OWNER FORMAT A15
COLUMN TABLE_NAME FORMAT A15
COLUMN TOMBSTONE_TABLE FORMAT A15
COLUMN ROW_RESOLUTION_COLUMN FORMAT A25
SELECT TABLE_OWNER,
TABLE_NAME,
TOMBSTONE_TABLE,
ROW_RESOLUTION_COLUMN
FROM ALL_GG_AUTO_CDR_TABLES
ORDER BY TABLE_OWNER, TABLE_NAME;
Your output looks similar to the following:
TABLE_OWNER TABLE_NAME TOMBSTONE_TABLE ROW_RESOLUTION_COLUMN
--------------- --------------- --------------- -------------------------
HR EMPLOYEES DT$_EMPLOYEES CDRTS$ROW
OE ORDERS DT$_ORDERS CDRTS$ROW
Parent topic: Monitoring Automatic Conflict Detection and Resolution
The ALL_GG_AUTO_CDR_COLUMNS
view displays information about the columns configured for Oracle GoldenGate automatic conflict detection and resolution.
The columns can be configured for row or column automatic conflict detection and resolution. The columns can be configured for latest timestamp conflict resolution in a column group. In addition, a column can be configured for delta conflict resolution.
ALL_GG_AUTO_CDR_COLUMNS
view.Example 16-11 Displaying Information About Column Groups
This query displays the following information about the tables that are configured for conflict detection and resolution:
The table owner for each table.
The table name for each table.
If the column is in a column group, then the name of the column group.
The column name.
If the column is configured for latest timestamp conflict resolution, then the name of the hidden timestamp column for the column.
COLUMN TABLE_OWNER FORMAT A10
COLUMN TABLE_NAME FORMAT A10
COLUMN COLUMN_GROUP_NAME FORMAT A17
COLUMN COLUMN_NAME FORMAT A15
COLUMN RESOLUTION_COLUMN FORMAT A23
SELECT TABLE_OWNER,
TABLE_NAME,
COLUMN_GROUP_NAME,
COLUMN_NAME,
RESOLUTION_COLUMN
FROM ALL_GG_AUTO_CDR_COLUMNS
ORDER BY TABLE_OWNER, TABLE_NAME;
Your output looks similar to the following:
TABLE_OWNE TABLE_NAME COLUMN_GROUP_NAME COLUMN_NAME RESOLUTION_COLUMN
---------- ---------- ----------------- --------------- -----------------------
HR EMPLOYEES COMPENSATION_CG COMMISSION_PCT CDRTS$COMPENSATION_CG
HR EMPLOYEES COMPENSATION_CG SALARY CDRTS$COMPENSATION_CG
HR EMPLOYEES JOB_IDENTIFIER_CG MANAGER_ID CDRTS$JOB_IDENTIFIER_CG
HR EMPLOYEES JOB_IDENTIFIER_CG JOB_ID CDRTS$JOB_IDENTIFIER_CG
HR EMPLOYEES JOB_IDENTIFIER_CG DEPARTMENT_ID CDRTS$JOB_IDENTIFIER_CG
HR EMPLOYEES IMPLICIT_COLUMNS$ PHONE_NUMBER CDRTS$ROW
HR EMPLOYEES IMPLICIT_COLUMNS$ LAST_NAME CDRTS$ROW
HR EMPLOYEES IMPLICIT_COLUMNS$ HIRE_DATE CDRTS$ROW
HR EMPLOYEES IMPLICIT_COLUMNS$ FIRST_NAME CDRTS$ROW
HR EMPLOYEES IMPLICIT_COLUMNS$ EMAIL CDRTS$ROW
HR EMPLOYEES IMPLICIT_COLUMNS$ EMPLOYEE_ID CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ ORDER_MODE CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ ORDER_ID CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ ORDER_DATE CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ CUSTOMER_ID CDRTS$ROW
OE ORDERS DELTA$ ORDER_TOTAL
OE ORDERS IMPLICIT_COLUMNS$ PROMOTION_ID CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ ORDER_STATUS CDRTS$ROW
OE ORDERS IMPLICIT_COLUMNS$ SALES_REP_ID CDRTS$ROW
In this example, the columns with IMPLICIT_COLUMNS$
for the column group name are configured for row conflict detection and resolution, but they are not part of a column group. The columns with DELTA$
for the column group name are configured for delta conflict detection and resolution, and these columns do not have a resolution column.
Parent topic: Monitoring Automatic Conflict Detection and Resolution
The ALL_GG_AUTO_CDR_COLUMN_GROUPS
view displays information about the column groups configured for Oracle GoldenGate automatic conflict detection and resolution.
You can configure Oracle GoldenGate automatic conflict detection and resolution using the ADD_AUTO_CDR
procedure in the DBMS_GOLDENGATE_ADM
package. You can configure column groups using the ADD_AUTO_CDR_COLUMN_GROUP
procedure in the DBMS_GOLDENGATE_ADM
package.
ALL_GG_AUTO_CDR_COLUMN_GROUPS
view.Example 16-12 Displaying Information About Column Groups
This query displays the following information about the tables that are configured for conflict detection and resolution:
The table owner.
The table name.
The name of the column group.
The hidden timestamp column used for conflict resolution for each column group.
COLUMN TABLE_OWNER FORMAT A15
COLUMN TABLE_NAME FORMAT A15
COLUMN COLUMN_GROUP_NAME FORMAT A20
COLUMN RESOLUTION_COLUMN FORMAT A25
SELECT TABLE_OWNER,
TABLE_NAME,
COLUMN_GROUP_NAME,
RESOLUTION_COLUMN
FROM ALL_GG_AUTO_CDR_COLUMN_GROUPS
ORDER BY TABLE_OWNER, TABLE_NAME;
The output looks similar to the following:
TABLE_OWNER TABLE_NAME COLUMN_GROUP_NAME RESOLUTION_COLUMN
--------------- --------------- -------------------- -------------------------
HR EMPLOYEES COMPENSATION_CG CDRTS$COMPENSATION_CG
HR EMPLOYEES JOB_IDENTIFIER_CG CDRTS$JOB_IDENTIFIER_CG
Parent topic: Monitoring Automatic Conflict Detection and Resolution