Use Native Oracle Log Reader (Beta) #

Note: This feature is currently in beta.

It’s possible to configure Replicant so that it can read and make use of Oracle redo log files.

Modify Oracle Connection Configuration File #

You need to set the following two parameters in the Oracle connection configuration file:

log-reader: {REDOLOG|REDOLOG_ARCHIVE_ONLY}
transaction-store-location: PATH_TO_TRANSACTION_STORAGE

Set log-reader to one of the following two values:

REDOLOG. Replicant extracts records from online log files as well as archive log files.
REDOLOG_ARCHIVE_ONLY. Replicant extracts records only from archive log files.

Replace PATH_TO_TRANSACTION_STORAGE with the path to a temporary location on the Arcion server. This temporary location stores information about uncommitted Oracle transactions that we track until they’re committed or rolled back.

Caution: If the source database often has a high number of long running uncommitted transactions, you need to increase the storage size to accommodate them.

Grant Necessary Permissions #

Replicant user should have the following permissions granted for them in order to use the native Oracle log reader.

GRANT SELECT ON gv_$instance TO USERNAME;
GRANT SELECT ON v_$log TO USERNAME;
GRANT SELECT ON v_$logfile TO USERNAME;
GRANT SELECT ON v_$archived_log to USERNAME;
GRANT SELECT ON dba_objects TO <USERNAME>;
GRANT SELECT ON v_$transportable_platform TO <USERNAME>;

Replace USERNAME with your Oracle username.

Choose How to Access Logs #

You can either use Oracle ASM to access the logs, or use the file system directly.

Oracle ASM #

Replicant supports using Oracle Automatic Storage Management (ASM) for logs. To use ASM, follow the steps below:

Make sure that the following permission is granted:
```
GRANT SELECT ON gv_$asm_client TO USERNAME
```
Replace USERNAME with your ASM username.
In your Oracle connection configuration file, create a new section asm-connection. This section will have the necessary ASM connection configuration. Below is a sample connection configuration file with ASM connection details specified as well:
```
type: ORACLE
host: localhost
port: 53545
service-name: IO
username: 'REPLICANT_USERNAME'
password: 'REPLICANT_PASSWORD'

asm-connection:
  host: oracle-asm
  port: 1521
  service-name: +ASM
  username: 'ASM_USERNAME'
  password: 'ASM_PASSWORD'
  max-connections: 10
```
Replace the following:
- REPLICANT_USERNAME: your Replicant username.
- REPLICANT_PASSWORD: the password associated with your Replicant username.
- ASM_USERNAME: the username to connect to the ASM instance.
- ASM_PASSWORD: the password associated with ASM_USERNAME.

File system #

To use the file system directly, Replicant must have access to the redo log files for reading. You can allow this access in one of the following two ways:

Share the locations of the redo log files directly with Replicant.
Multiplex the redo log files to an alternative location and make that location accessible to Replicant.

If you decide to multiplex the redo log files, you must specify the paths in the source connection configuration file using the log-path and archive-log-path parameters:

log-path: PATH_TO_MULTIPLEXED_ONLINE_REDO_LOG_FILES
archive-log-path: PATH_TO_MULTIPLEXED_ARCHIVE_REDO_LOG_FILES

Replace the following:

PATH_TO_MULTIPLEXED_ONLINE_REDO_LOG_FILES: path to the location on the disk where the online redo logs are multiplexed
PATH_TO_MULTIPLEXED_ARCHIVE_REDO_LOG_FILES: path to the location on the disk where the archived redo logs are multiplexed

If Replicant’s path(s) to redo log files is different from the database’s path, you must include the path(s) explicitly in the source connection configuration file using the alt-log-path and alt-archive-log-path parameters:

alt-log-path: REPLICANT_PATH_TO_ONLINE_REDO_LOG_FILES
alt-archive-log-path: REPLICANT_PATH_TO_ARCHIVE_REDO_LOG_FILES

Replace the following:

REPLICANT_PATH_TO_ONLINE_REDO_LOG_FILES: path to the online redo logs relative to Replicant
REPLICANT_PATH_TO_ARCHIVE_REDO_LOG_FILES: path to the archived redo logs relative to Replicant