Step 2.5.1: Extract configuration

When creating an Extract using the Oracle GoldenGate Administration Service interface, leave the Trail Subdirectory parameter blank so that the trail files are automatically created in the deployment directories stored on the shared file system. The default location for trail files is the /<deployment directory>/var/lib/data directory.

For GoldenGate Extract processes using Data Guard configurations that are using redo transport Maximum Performance or Maximum Availability modes, the following parameter must be added to the Extract process parameter file on the primary system to avoid losing transactions and resulting in logical data inconsistencies:

TRANLOGOPTIONS HANDLEDLFAILOVER

This parameter prevents Extract from extracting transaction data from redo that has not yet been applied to the Data Guard standby database. This is crucial to preventing Oracle GoldenGate from replicating data to a target database that does not exist in the source standby database.

If this parameter is not specified, after a data loss failover of the source database it is possible to have data in the target database that is not present in the source database, leading to logical data inconsistencies.

By default, after 60 seconds, a warning message will be written to the Extract report file when the Extract is stalled due to not being able to query the standby database applied SCN information. For example:

WARNING OGG-02721  Extract has been waiting for the standby database for 60 seconds.

The amount of time before the warning message is written to Extract report file can be adjusted using the Extract parameter "TRANLOGOPTIONS HANDLEDLFAILOVER STANDBY_WARNING".

If the Extract is still not able to query the standby database applied SCN information after 30 minutes (default), the Extract process will abend, logging the following message in the Extract report file:

ERROR   OGG-02722  Extract abended waiting for 1,800 seconds for the
    standby database to be accessible or caught up with the primary database.

If the standby database becomes available before the default 30 timeout expires, Extract continues mining data from the source database and reports the following message to the report file:

INFO    OGG-02723  Extract resumed from stalled state and started
    processing LCRs.

The timeout value of 30 minutes can be adjusted using the Extract parameter "TRANLOGOPTIONS HANDLEDLFAILOVER STANDBY_ABEND <value>", where value is the number of seconds the standby is unavailable before abending.

If the standby database will be unavailable for a prolonged duration, such as during a planned maintenance outage, and you wish Extract to continue extracting data from the primary database, remove the "TRANLOGOPTIONS HANDLEDLFAILOVER" parameter from the Extract parameter file and restart Extract (see example below in Figures 4 to 6). Remember to set the parameter after the standby becomes available.

If the Extract process has been assigned an auto restart profile, after a Data Guard role transition, the Extract process will automatically restart. Extract will continue to mine redo data from the new primary database, ignoring the current state of the new standby database, until a default 5-minute timeout period expires. After this time, if the standby is not available Extract will abend with the following errors:

INFO    OGG-25053  Timeout waiting for 300 seconds for standby database
 reinstatement. Now enforcing HANDLEDLFAILOVER.
ERROR   OGG-06219  Unable to extract data from the Logmining server OGG$CAP_XXXXX.
ERROR   OGG-02078  Extract encountered a fatal error in a processing thread and is
 abending.

Extract will continue to automatically restart, based on the GoldenGate Microservices auto restart profile, and failing due to reaching the HANDLEDLFAILOVER timeout, until the number retries is reached or the new standby database becomes available.

During the timeout period following a database role transition, the HANDLEDLFAILOVER parameter is automatically suspended, so data will be replicated to the Oracle GoldenGate replica database without consideration of the source standby database not being kept up to date. The timeout period for the standby database to start up before Extract abends can be adjusted using the Extract parameter TRANLOGOPTIONS DLFAILOVER_TIMEOUT.

It is recommended that you leave DLFAILOVER_TIMEOUT at the default of 5 minutes, to allow the old primary to convert to a standby. If the new standby database will be unavailable for an extended period of time or completely gone, then in order for Extract to start and remain running, you must remove the HANDLEDLFAILOVER parameter from the Extract parameter file. After removing the parameter, Extract no longer waits until redo has been applied to the standby database before extracting the data.

During the time it takes for the standby database to come back online and apply all the redo from the primary database, there will be data divergence between it and the Oracle GoldenGate replica database. This will be resolved once the standby database is up to date. At which point, add the HANDLEDLFAILOVER parameter back into the integrated Extract process parameter file, and then stop and restart the Extract.

When Oracle Data Guard Fast-Start Failover is disabled, such that the broker can automatically fail over to a standby database in the event of loss of the primary database, you must specify an additional integrated Extract parameter shown below.

TRANLOGOPTIONS FAILOVERTARGETDESTID n

This parameter identifies which standby database the Oracle GoldenGate Extract process must remain behind, with regards to not extracting redo data that has not yet been applied to the standby database.

If Oracle Data Guard Fast-Start Failover is disabled, and you don’t specify the additional integrated Extract parameter FAILOVERTARGETDESTID, the extract will abend with the following errors:

ERROR OGG-06219 Unable to extract data from the Logmining server OGG$CAP_XXXXX.
ERROR OGG-02078 Extract encountered a fatal error in a processing thread and is
 abending.

To determine the correct value for FAILOVERTARGETDESTID, use the LOG_ARCHIVE_DEST_N parameter from the GoldenGate source database which is used for sending redo to the source standby database. For example, if LOG_ARCHIVE_DEST_2 points to the standby database, then use a value of 2.

As the oracle user on the primary database system, execute the following command:

[opc@exapri-node1 ~]$ sudo su - oracle
[oracle@exapri-node1 ~]$ source <db_name>.env
[oracle@exapri-node1 ~]$ sqlplus / as sysdba

SQL> show parameters log_archive_dest

NAME                  TYPE        VALUE
--------------------- ----------- ---------------------------------------------------
log_archive_dest_1    string      location=USE_DB_RECOVERY_FILE_DEST,
                                  valid_for=(ALL_LOGFILES, ALL_ROLES)

log_archive_dest_2    string      service="<db_name>", SYNC AFFIRM delay=0 
                                  optional compression=disable max_failure=0 reopen=300
                                  db_unique_name="<db_name>" net_timeout=30, 
                                  valid_for=(online_logfile,all_roles)

In this example, the Extract parameter would be set to the following:

TRANLOGOPTIONS FAILOVERTARGETDESTID 2

Create the Extract:

1. Log in to the Oracle GoldenGate Administration Server
2. Click in Overview under Administration Service
3. Click the plus button to Add Extract
4. Select Integrated Extract
5. Add the required information as follows:
   • Process Name: EXT_1
   • Description: Extract for Region 1 CDB
   • Intent: Unidirection
   • Begin: Now
   • Trail Name: aa
   • Credential Domain: GoldenGate
   • Credential Alias: Reg1_CDB
   • Register to PDBs: PDB Name
6. Click Next
7. If using CDB Root Capture from PDB, add the SOURCECATALOG parameter with the PDB Name
8. Click Create and Run

Step 2.5.2 - Replicat configuration

Oracle generally recommends using integrated parallel Replicat which offers better apply performance for most workloads when the GGHUB is in the same region as the target Oracle GoldenGate database.

The best apply performance can be achieved when the network latency between the GGHUB and the target database is as low as possible. The following configuration is recommended for the remote Replicat running on the Oracle GGHUB.

• APPLY_PARALLELISM – Disables automatic parallelism, instead of using MAX_APPLY_PARALLELISM and MIN_APPLY_PARALLELISM, and allows the highest amount of concurrency to the target database. It is recommended to set this as high as possible based on available CPU of the hub and the target database server.
• MAP_PARALLELISM – Should be set with a value of 2 to 5. With a larger number of appliers, increasing the Mappers increases the ability to hand work to the appliers.
• BATCHSQL – applies DML using array processing which reduces the amount network overheads with a higher latency network. Be aware that if there are many data conflicts, BATCHSQL results in reduced performance, as rollback of the batch operations followed by a re-read from trail file to apply in non-batch mode.

Step 2.5.3 - Distribution Path configuration

Distribution paths are only necessary when trail files need to be sent to an additional Oracle GoldenGate Hub in a different, or even the same, region as described in the following figure.

When using Oracle GoldenGate Distribution paths with the NGINX Reverse Proxy, additional steps must be carried out to ensure the path client and server certificates are configured.

More instructions about creating distribution paths are available in Using Oracle GoldenGate Microservices Architecture. A step-by-step example is in the following video, “Connect an on-premises Oracle GoldenGate to OCI GoldenGate using NGINX,” to correctly configure the certificates.

Here are the steps performed in this sub-step:

• Step 2.5.3.1 - Download the Target Server’s Root Certificate, and then upload it to the source Oracle GoldenGate
• Step 2.5.3.2 - Create a user in the Target Deployment for the Source Oracle GoldenGate to use
• Step 2.5.3.3 - Create a Credential in the Source Oracle GoldenGate
• Step 2.5.3.4 - Create a Distribution Path on the Source Oracle GoldenGate to the Target Deployment
• Step 2.5.3.5 - Verify the Connection in the Target Deployment Console Receiver Service

Step 2.5.3.1 - Download the Target Server’s Root Certificate, and then upload it to the source Oracle GoldenGate

Download the target deployment server’s root certificate and add the CA certificate to the source deployment Service Manager.

1. Log in to the Administration Service on the Target GoldenGate.
2. Follow “Step 2 - Download the target server’s root certificate” in the video “Connect an on-premises Oracle GoldenGate to OCI GoldenGate using NGINX.”

Step 2.5.3.2 - Create a user in the Target Deployment for the Source Oracle GoldenGate to use

Create a user in the target deployment for the distribution path to connect to:

1. Log in to the Administration Service on the Target GoldenGate.
2. Click on Administrator under Administration Service.
3. Click the plus (+) sign next to Users.
4. Enter the details as follows:
   • Username: ggnet
   • Role: Operator
   • Type: Password
5. Click Submit

Step 2.5.3.3 - Create a Credential in the Source Oracle GoldenGate

Create a credential in the source deployment connecting the target deployment with the user created in the previous step. For example, a domain of OP2C and an alias of WSSNET.

1. Log in to the Administration Service on the Source Oracle GoldenGate.
2. Click in Configuration under Administration Service.
3. Click the plus (+) sign next to Credentials on the Database home page.
4. Enter the details as follows:
   • Credential Domain: OP2C
   • Credential Alias: wssnet
   • User ID: ggnet
5. Click Submit

Step 2.5.3.4 - Create a Distribution Path on the Source Oracle GoldenGate to the Target Deployment

A path is created to send trail files from the Distribution Server to the Receiver Server. You can create a path from the Distribution Service. To add a path for the source deployment:

1. Log in to the Distribution Service on the Source Oracle Goldengate.
2. Click the plus (+) sign next to Path on the Distribution Service home page. The Add Path page is displayed.
3. Enter the details as follows:

   Option	Description
   Path Name	Select a name for the path.
   Source: Trail Name	Select the Extract name from the drop-down list, which populates the trail name automatically. If it doesn’t, enter the trail name you provided while adding the Extract.
   Generated Source URI	Specify localhost for the server’s name; this allows the distribution path to be started on any of the Oracle RAC nodes.
   Target Authentication Method	Use ‘UserID Alias’
   Target	Set the Target transfer protocol to wss (secure web socket). Set the Target Host to the target hostname/VIP that will be used for connecting to the target system along with the Port Number that NGINX was configured with (default is 443).
   Domain	Set the Domain to the credential domain created above in Step 2.3.3.3, for example, OP2C.
   Alias	The Alias is set to the credential alias wssnet, also created in Step 2.3.3.3.
   Auto Restart Options	Set the distribution path to restart when the Distribution Server starts automatically. This is required, so that manual intervention is not required after a RAC node relocation of the Distribution Server. It is recommended to set the number of Retries to 10. Set the Delay, which is the time in minutes to pause between restart attempts, to 1.

4. Click Create Path.
5. From the Action Menu, click Start.