Failover and Recovery Operations

Learn how Oracle GoldenGate provides failover support for PostgreSQL, performs bounded recovery for Oracle, and allows MySQL to start from specific position in log, based on the log number and log offset values.

Positioning Extract to a Specific Start Point

You can position the Extract to a specific start point in the transaction logs. You can set this from the web interface, Admin Client, or the REST API service endpoint.

If you are creating an Extract then you must perform the following steps to start the newly created Extract at a specific position in the database: 1. Add the Extract with the BEGIN NOW option, as shown in the following example:

<pre class="copy"><code>ADD EXTRACT extn, TRANLOG, BEGIN NOW</code></pre>

1. Register the Extract.

   REGISTER EXTRACT extn DATABASE

2. Alter this Extract and specify the timestamp.

   ALTER EXTRACT extn BEGIN 2020-08-02T06:05:30.000Z

Web Interface

To position an Extract to a specific start point in the database: 1. Stop the Extract if it’s running.

1. From the Actions column, click the three-dot icon and click Alter.

2. From the Alter Extract dialog box, click the Begin option and select Custom Time.

3. Select the timestamp from the Custom Time field and select the Timezone.

4. Click Submit.

5. Restart the Extract by clicking the Play icon from the Action column.

Admin Client

To position an Extract using the ADD/ALTER EXTRACT commands:

{ADD | ALTER EXTRACT} *group*, LOGNUM *log_num*, LOGPOS *log_pos*

• group is the name of the Oracle GoldenGate Extract group for which the start position is required.

• LOGNUM is the log file number. For example, if the required log file name is test.000034, the LOGNUM value is 34. Extract will search for this log file. TheADD EXTRACT command will fail if the LOGNUM value contains zeroes preceding the value. For example, ADD EXTRACT extn, TRANLOG, LOGNUM 000001, LOGPOS 0 will fail. Instead, set LOGNUM to 1 for this example to succeed.

• LOGPOS is an event offset value within the log file that identifies a specific transaction record. Event offset values are stored in the header section of a log record. To position at the beginning of a binlog file, set the LOGPOS as 0.