B Configuring a Downstream Mining Database
For more information about integrated capture, see Deciding Which Capture Method to Use.
For examples of the downstream mining configuration, see Example Downstream Mining Configuration.
Topics:
- Evaluating Capture Options for a Downstream Deployment
Downstream deployment allows you to offload the source database. - Preparing the Source Database for Downstream Deployment
The source database ships its redo logs to a downstream database, and Extract uses the logmining server at the downstream database to mine the redo logs. - Preparing the Downstream Mining Database
A downstream mining database can accept both archived logs and online redo logs from a source database.
Evaluating Capture Options for a Downstream Deployment
Downstream deployment allows you to offload the source database.
A downstream mining database can accept both archived logs and online redo logs from a source database.
Multiple source databases can send their redo data to a single downstream database; however the downstream mining database can accept online redo logs from only one of those source databases. The rest of the source databases must ship archived logs.
When online logs are shipped to the downstream database, real-time capture by Extract is possible. Changes are captured as though Extract is reading from the source logs. In order to accept online redo logs from a source database, the downstream mining database must have standby redo logs configured.
When using a downstream mining configuration, the source database and mining database must be the same endian and same bitsize, which is 64 bits. For example, if the source database was on Linux 64-bit, you can have the mining database run on Windows 64-bit, because they have the same endian and bitsize.Parent topic: Configuring a Downstream Mining Database
Preparing the Source Database for Downstream Deployment
The source database ships its redo logs to a downstream database, and Extract uses the logmining server at the downstream database to mine the redo logs.
This section guides you in the process of:
- Creating the Source User Account
- Configuring Redo Transport from Source to Downstream Mining Database
To set up the transfer of redo log files from a source database to the downstream mining database, and to prepare the downstream mining database to accept these redo log files, perform the steps given in this topic.
Parent topic: Configuring a Downstream Mining Database
Creating the Source User Account
There must be an Extract user on the source database. Extract uses the credentials of this user to do metadata queries and to fetch column values as needed from the source database. The source user is specified by the USERIDALIAS
parameter.
To assign the required privileges, follow the procedure in Establishing Oracle GoldenGate Credentials
Parent topic: Preparing the Source Database for Downstream Deployment
Configuring Redo Transport from Source to Downstream Mining Database
To set up the transfer of redo log files from a source database to the downstream mining database, and to prepare the downstream mining database to accept these redo log files, perform the steps given in this topic.
The following summarizes the rules for supporting multiple sources sending redo to a single downstream mining database:
-
Only one source database can be configured to send online redo to the standby redo logs at the downstream mining database. The
log_archive_dest_n
setting for this source database should not have aTEMPLATE
clause. -
Source databases that are not sending online redo to the standby redo logs of the downstream mining database must have a
TEMPLATE
clause specified in thelog_archive_dest_n
parameter. -
Each of the source databases that sends redo to the downstream mining database must have a unique
DBID
. You can select theDBID
column from thev$database
view of these source databases to ensure that the DBIDs are unique. -
The
FAL_SERVER
value must be set to the downstream mining database.FAL_SERVER
specifies the FAL (fetch archive log) server for a standby database. The value is a list of Oracle Net service names, which are assumed to be configured properly on the standby database system to point to the desired FAL servers. The list contains the net service name of any database that can potentially ship redo to the downstream database. -
When using redo transport, there could be a delay in processing redo due to network latency. In case of Integrated Extract, this latency is monitored by measuring the delay between LCRs received from source database and reporting it. If the latency exceeds a threshold, a warning message appears in the report file and a subsequent information message appears when the lag drops to normal values. The default value for the threshold is 10 seconds.
Note:
The archived logs shipped from the source databases are called foreign archived logs. You must not use the recovery area at the downstream mining database to store foreign archived logs. Such a configuration is not supported by Integrated Capture.
These instructions take into account the requirements to ship redo from multiple sources, if required. You must configure an Extract process for each of those sources.
To Configure Redo Transport
Parent topic: Preparing the Source Database for Downstream Deployment
Preparing the Downstream Mining Database
A downstream mining database can accept both archived logs and online redo logs from a source database.
The following sections explain how to prepare the downstream mining database:
- Creating the Downstream Mining User Account
- Configuring the Mining Database to Archive Local Redo Log Files
- Preparing a Downstream Mining Database for Real-time Capture
Parent topic: Configuring a Downstream Mining Database
Creating the Downstream Mining User Account
When using a downstream mining configuration, there must be an Extract mining user on the downstream database. The mining Extract process uses the credentials of this user to interact with the downstream logmining server. The downstream mining user is specified by the TRANLOGOPTIONS
parameter with the MININGUSERALIAS
option. See Establishing Oracle GoldenGate Credentials to assign the correct credentials for the version of your database.
Parent topic: Preparing the Downstream Mining Database
Configuring the Mining Database to Archive Local Redo Log Files
This procedure configures the downstream mining database to archive redo data in its online redo logs. These are redo logs that are generated at the downstream mining database.
Archiving must be enabled at the downstream mining database if you want to run Extract in real-time integrated capture mode, but it is also recommended for archive-log-only capture. Extract in integrated capture mode writes state information in the database. Archiving and regular backups will enable you to recover this state information in case there are disk failures or corruption at the downstream mining database.
To Archive Local Redo Log Files
For more information about these initialization parameters, see Oracle Data Guard Concepts and Administration.
Parent topic: Preparing the Downstream Mining Database
Preparing a Downstream Mining Database for Real-time Capture
This procedure is only required if you want to use real-time capture at a downstream mining database. It is not required to use archived-log-only capture mode. To use real-time capture, it is assumed that the downstream database has already been configured to archive its local redo data as shown in Configuring the Mining Database to Archive Local Redo Log Files.
Parent topic: Preparing the Downstream Mining Database
Create the Standby Redo Log Files
The following steps outline the procedure for adding standby redo log files to the downstream mining database. The following summarizes the rules for creating the standby redo logs:
-
Each standby redo log file must be at least as large as the largest redo log file of the redo source database. For administrative ease, Oracle recommends that all redo log files at source database and the standby redo log files at the downstream mining database be of the same size.
-
The standby redo log must have at least one more redo log group than the redo log at the source database, for each redo thread at the source database.
The specific steps and SQL statements that are required to add standby redo log files depend on your environment. See Oracle Data Guard Concepts and Administration 11g Release 2 (11.2) for detailed instructions about adding standby redo log files to a database.
Note:
If there will be multiple source databases sending redo to a single downstream mining database, only one of those sources can send redo to the standby redo logs of the mining database. An Extract process that mines the redo from this source database can run in real-time mode. All other source databases must send only their archived logs to the downstream mining database, and the Extracts that read this data must be configured to run in archived-log-only mode.
To Create the Standby Redo Log Files
Configure the Database to Archive Standby Redo Log Files Locally
This procedure configures the downstream mining database to archive the standby redo logs that receive redo data from the online redo logs of the source database. Keep in mind that foreign archived logs should not be archived in the recovery area of the downstream mining database.
To Archive Standby Redo Logs Locally