Native Log Reader

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 must possess the following permissions in order to use the native Oracle log reader.

Click to see the list of permissions 
GRANT CREATE SESSION TO <USERNAME>;
GRANT EXECUTE_CATALOG_ROLE TO <USERNAME>;
GRANT SELECT ANY TABLE TO <USERNAME>;
GRANT SELECT ON all_constraints TO <USERNAME>;
GRANT SELECT ON all_cons_columns TO <USERNAME>;
GRANT SELECT ON all_indexes TO <USERNAME>;
GRANT SELECT ON all_ind_expressions TO <USERNAME>;
GRANT SELECT ON all_part_tables TO <USERNAME>;
GRANT SELECT ON all_part_key_columns TO <USERNAME>;
GRANT SELECT ON all_tables TO <USERNAME>;
GRANT SELECT ON all_tab_columns TO <USERNAME>;
GRANT SELECT ON all_views TO <USERNAME>;
GRANT SELECT ON dba_constraints TO <USERNAME>;
GRANT SELECT ON dba_cons_columns TO <USERNAME>;
GRANT SELECT ON dba_indexes TO <USERNAME>;
GRANT SELECT ON dba_ind_columns TO <USERNAME>;
GRANT SELECT ON dba_lobs TO <USERNAME>;
GRANT SELECT ON dba_objects TO <USERNAME>;
GRANT SELECT ON dba_roles TO <USERNAME>;
GRANT SELECT ON dba_tables TO <USERNAME>;
GRANT SELECT ON dba_tab_cols TO <USERNAME>;
GRANT SELECT ON gv_$database TO <USERNAME>;
GRANT SELECT ON gv_$instance TO <USERNAME>;
GRANT SELECT ON gv_$transaction TO <USERNAME>;
GRANT SELECT ON v_$archived_log to <USERNAME>;
GRANT SELECT ON v_$database TO <USERNAME>;
GRANT SELECT ON v_$log TO <USERNAME>;
GRANT SELECT ON v_$logfile TO <USERNAME>;
GRANT SELECT ON v_$transportable_platform TO <USERNAME>;

Replace <USERNAME> with your Oracle username.

For Oracle pluggable database, you must add CONTAINER clause to the preceding GRANT statements.

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 these steps:

  1. Grant the following permissions to Replicant:

    GRANT SELECT ON gv_$asm_client TO USERNAME

  2. In your Oracle connection configuration file, create a new section asm-connection that contains the necessary ASM connection details:

    type: ORACLE
...

asm-connection:
  host: //ASM_HOSTNAME
  port: 1521
  service-name: +ASM
  username: 'ASM_USERNAME'
  password: 'ASM_PASSWORD'
  max-connections: 10

    Replace the following:

    • ASM_HOSTNAME: the hostname of the ASM instance. Make sure to prefix the hostname with //.
    • 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

Oracle RAC #

The native log reader supports Oracle RAC active-passive and active-active CDB/PDB environments with automatic failover, while manually handling new instance additions. Follow below steps for setup:

  • The SCAN name must be specified as a host name.

    host: SCAN_NAME

  • In the active-passive case, ensure that either only one instance is running, or the service associated with the PDB or CDB is running on only one instance.

  • In the active-active case, set the value of rac-configuration tag to ACTIVE_ACTIVE. The default value is ACTIVE_PASSIVE.

    rac-configuration: ACTIVE_ACTIVE