Prepare for log archiving

This section describes the preparations for log archiving.

(Optional) Configure the log archiving concurrency

Before you enable the archiving mode, you can configure the log archiving concurrency to improve the log archiving speed of the tenant.

1. Log in to the database as the sys tenant or the tenant administrator of a user tenant.

2. Choose a suitable statement to set the log_archive_concurrency parameter.

   The tenant-level log_archive_concurrency parameter specifies the total number of working threads for log archiving. This parameter takes effect dynamically without requiring a restart of the OBServer node. The value of this parameter ranges from 0 to 100, with a default value of 0, indicating the use of the adaptive log archiving concurrency of OceanBase Database. We recommend that you use the default value.

   Notice

   For small-scale tenants (tenants with CPU cores less than or equal to 4), we recommend that you use the default value and do not modify the value of this parameter.

   You can set this parameter as follows:

   • Adjust the log archiving concurrency of a specified tenant in the sys tenant.

     ALTER SYSTEM SET log_archive_concurrency = 10 TENANT = mysql_tenant;
     

   • Adjust the log archiving concurrency of all tenants in the sys tenant.

     ALTER SYSTEM SET log_archive_concurrency = 10 TENANT = all_user;
     

     or

     ALTER SYSTEM SET log_archive_concurrency = 10 TENANT = all;
     

     Note

     Starting from OceanBase Database V4.2.1, the TENANT = all_user and TENANT = all clauses have the same semantics. When you want to apply the setting to all user tenants, we recommend that you use the TENANT = all_user clause. The TENANT = all clause will be deprecated and no longer supported.

   • Adjust the log archiving concurrency of the current tenant in a user tenant.

     ALTER SYSTEM SET log_archive_concurrency = 10;
     

   For more information about the log_archive_concurrency parameter, see log_archive_concurrency.

Configure the archive destination

Before you start a log archiving task, you need to use the ALTER SYSTEM command to configure the LOG_ARCHIVE_DEST parameter. Since the sys tenant is a cluster management tenant that does not contain user data, it does not support backup and restore. Therefore, you do not need to configure the archive destination for the sys tenant.

The main operations for configuring the archive destination are to set the LOCATION, BINDING, and PIECE_SWITCH_INTERVAL attributes.

Considerations

When you configure the destination for archiving, you must configure an independent empty directory for each tenant as the archive path. Different tenants cannot use the same archive path.

Procedure

1. Log in as a tenant administrator of the sys tenant or a user tenant.

   Note

   In MySQL-compatible mode, the administrator user is root. In Oracle-compatible mode, the administrator user is SYS.

2. Set the archive destination.

   Notice

   For an upgrade from OceanBase Database V4.0.x to V4.1.0, you must modify the archive log path after the upgrade. For an upgrade from OceanBase Database V4.1.x to V4.2.x, you do not need to modify the archive log path after the upgrade. In addition, you can perform log archiving during an upgrade from OceanBase Database V4.1.x to V4.2.x.

   • The sys tenant configures the archive destination for a specified tenant

     ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=archive_path [BINDING=archive_mode] [PIECE_SWITCH_INTERVAL=piece_switch_interval]' TENANT = tenant_name;
     

   • The user tenant configures the archive destination for the current tenant

     ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=archive_path [BINDING=archive_mode] [PIECE_SWITCH_INTERVAL=piece_switch_interval]';
     

   The detailed configuration is as follows.

   • Configure LOCATION (required)

     The LOCATION attribute specifies the archive path. Currently, OceanBase Database supports NFS, Alibaba Cloud OSS, Azure Blob (supported starting from V4.2.5 BP6 in V4.2.5), AWS S3, and S3-compatible object storage such as Huawei OBS, Google GCS, and Tencent Cloud COS as archive media. Some archive media may need to meet basic requirements before use. For the specific requirements of each archive medium, see Backup media requirements in Overview of physical backup and restore.

     Alibaba Cloud OSS

     NFS

     AWS S3

     S3-compatible object storage

     Azure Blob

     When you use OSS as the archive medium, you can set the delete_mode parameter in addition to the archive path, host, access_id, and access_key. The delete_mode parameter supports delete mode and tagging mode. If you do not explicitly set the delete_mode parameter, delete mode is used by default.

     OSS also supports the checksum_type parameter to specify the algorithm used to verify the integrity of archive files. Valid values are md5 and no_checksum. If you do not explicitly set the checksum_type parameter, the default value is md5.

     In OceanBase Database V4.2.5, starting from V4.2.5 BP7, you can use an Alibaba Cloud OSS bucket with a compliance retention policy configured as the archive path. When you configure an archive path, you can use the enable_worm parameter to specify whether OceanBase Database performs write and delete operations on the path according to the bucket retention policy (WORM policy). Valid values are true and false. If you do not explicitly set the enable_worm parameter, the default value is false. When you set enable_worm=true, you must also explicitly set checksum_type=md5. After this parameter is set, it cannot be changed.

     Notice

     OceanBase Database does not configure a compliance retention policy for you. Before you set the archive path, make sure that the OSS bucket retention policy (WORM policy) has been properly configured and locked.

     For more information about the parameters, see SET LOG_ARCHIVE_DEST.

     Notice

     If you use an object storage service as the archival storage medium, the object storage path parameters are separated by the & symbol. Ensure that the parameters you enter contain only English letters, numbers, /-_$+=, and wildcards. If you use other characters, the setting may fail.

     Examples:

     • When you use OSS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant, sets the cleanup mode to delete, and specifies the verification algorithm as md5.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=oss://oceanbase-test-bucket/backup/archive?host=****.aliyun-inc.com&access_id=****&access_key=****&delete_mode=delete&checksum_type=md5' TENANT = mysql_tenant;
       

       If you do not want to verify the integrity of archive files, set the checksum_type parameter to no_checksum. Example:

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=oss://oceanbase-test-bucket/backup/archive?host=****.aliyun-inc.com&access_id=****&access_key=****&delete_mode=delete&checksum_type=no_checksum' TENANT = mysql_tenant;
       

     • When you use OSS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant, sets the cleanup mode to tagging, specifies WORM-compliant object write and delete operations, and sets the verification algorithm to md5.

       Notice

       • OceanBase Database does not configure a compliance retention policy for you. Before you set the archive path, make sure that the OSS bucket retention policy (WORM policy) has been properly configured and locked.
       • When you use a bucket with a WORM policy as the archive path, we recommend that you use the tagging cleanup mode.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=oss://oceanbase-test-bucket/backup/archive?host=****.aliyun-inc.com&access_id=****&access_key=****&delete_mode=tagging&checksum_type=md5&enable_worm=true' TENANT = mysql_tenant;
       

     • When you use OSS as the archive medium, the user tenant sets the archive path for the current tenant, sets the cleanup mode to delete, and specifies the verification algorithm as md5.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=oss://oceanbase-test-bucket/backup/archive?host=****.aliyun-inc.com&access_id=****&access_key=****&delete_mode=delete&checksum_type=md5';
       

     In the examples, oss:// indicates that OSS is used as the archive medium. The bucket name is oceanbase-test-bucket, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the host address of the bucket. access_id and access_key specify the access keys for OSS. delete_mode=delete indicates that the cleanup mode is delete, and the MD5 algorithm is used to verify the integrity of archive files. enable_worm=true indicates that write and delete operations are performed according to WORM rules. OceanBase Database does not configure a compliance retention policy for you. Before you set the archive path, make sure that the OSS bucket retention policy (WORM policy) has been properly configured and locked.

     Notice

     When you use NFS as the archive medium, note the following:

     • The value of LOCATION cannot be set to a string that contains a question mark (?) character.
     • LOCATION must be set to an absolute path, ensuring that the OBServer server has read and write permissions for LOCATION.
     • Make sure that all OBServer nodes have mounted the same NFS server. To ensure smooth archiving, use the recommended parameters to mount the NFS server. For more information about how to mount the NFS server, see Deploy NFS Clients.

     Examples:

     • When you use NFS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive' TENANT = mysql_tenant;
       

     • When you use NFS as the archive medium, the user tenant sets the archive path for the current tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive';
       

     In the example, file:// indicates that NFS is used as the archive medium, and the archive path is /data/nfs/backup/archive.

     Like OSS, AWS S3 supports the delete_mode parameter to configure the cleanup mode of archive files. The configuration method is the same as that for OSS. AWS S3 also supports the checksum_type parameter to specify the algorithm used to verify the integrity of archive files. Valid values are md5 and crc32. If you do not explicitly set the checksum_type parameter, the default value is md5.

     For more information about the delete_mode and checksum_type parameters, see SET LOG_ARCHIVE_DEST.

     Notice

     When you use object storage as the archive medium, the parameters in the object storage path are separated by the & symbol. Make sure that the parameter values contain only uppercase and lowercase English letters, digits, /-_$+=, and wildcards. If you enter other characters, the setting may fail.

     Examples for using S3 as the archive medium:

     • When you use S3 as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant, sets the cleanup mode to delete, and specifies the verification algorithm as crc32.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=s3.<region>.amazonaws.com&access_id=******&access_key=******&s3_region=******&delete_mode=delete&checksum_type=crc32' TENANT = mysql_tenant;
       

     • When you use S3 as the archive medium, the user tenant sets the archive path for the current tenant, sets the cleanup mode to delete, and specifies the verification algorithm as crc32.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=s3.<region>.amazonaws.com&access_id=******&access_key=******&s3_region=******&delete_mode=delete&checksum_type=crc32';
       

     In the examples, s3:// indicates that AWS S3 is used as the archive medium. The bucket name is oceanbase-test-bucket, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the domain name of the Amazon S3 service. access_id and access_key specify the access keys for AWS. s3_region is required when S3 is used as the archive medium and specifies the region of the S3 bucket. The cleanup mode is delete, and the CRC32 algorithm is used to verify the integrity of archive files.

     For more information about the AWS S3 path format, see Appendix: AWS S3 Path Format Description.

     Because most object storage services are compatible with the S3 protocol, any S3-compatible object storage that meets OceanBase Database requirements (the object storage must implement the S3 API behaviors used by OceanBase system calls) can be used as an archive medium and accessed through the S3 protocol. For example, OBS, GCS, and COS are all accessed through the S3 protocol.

     For OBS, GCS, and COS object storage accessed through the S3 protocol, you can use the checksum_type parameter to specify the algorithm used to verify the integrity of archive files. Only md5 is supported. If you do not explicitly set the checksum_type parameter, the default value is md5. For more information about the checksum_type parameter, see SET LOG_ARCHIVE_DEST.

     Notice

     • When you use object storage as the archive medium, the parameters in the object storage path are separated by the & symbol. Make sure that the parameter values contain only uppercase and lowercase English letters, digits, /-_$+=, and wildcards. If you enter other characters, the setting may fail.
     • For some S3-compatible object storage services, the default URL encoding method of the AWS S3 SDK may not be supported. If errors such as 9129 or 9026 occur when you access object storage through the s3:// protocol, set the cluster-level parameter ob_storage_s3_url_encode_type to make the URL encoding method used by AWS S3 compatible with the RFC 3986 standard. For detailed steps, see Steps and examples for using COS as the archive medium below.

     Examples for using OBS as the archive medium:

     • When you use OBS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=obs.****.myhuaweicloud.com&access_id=****&access_key=****' TENANT = mysql_tenant;
       

     • When you use OBS as the archive medium, the user tenant sets the archive path for the current tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=obs.****.myhuaweicloud.com&access_id=****&access_key=****';
       

     In the examples, s3:// indicates that S3-compatible object storage is used as the archive medium. The bucket name is oceanbase-test-bucket, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the domain name of the OBS service. access_id and access_key specify the access keys for OBS.

     Examples for using GCS as the archive medium:

     • When you use GCS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=https://storage.googleapis.com&access_id=****&access_key=****' TENANT = mysql_tenant;
       

     • When you use GCS as the archive medium, the user tenant sets the archive path for the current tenant.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test-bucket/backup/archive?host=https://storage.googleapis.com&access_id=****&access_key=****';
       

     In the examples, s3:// indicates that S3-compatible object storage is used as the archive medium. The bucket name is oceanbase-test-bucket, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the domain name of the GCS service. access_id and access_key specify the access keys for GCS.

     Steps and examples for using COS as the archive medium:

     1. Check the value of the ob_storage_s3_url_encode_type parameter at the cluster level.

        obclient> SHOW PARAMETERS LIKE '%ob_storage_s3_url_encode_type%';
        

        The result is as follows:

        +-------+----------+----------------+----------+-------------------------------+-----------+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+
        | zone  | svr_type | svr_ip         | svr_port | name                          | data_type | value   | info                                                                                                                                                                                        | section  | scope   | source  | edit_level        |
        +-------+----------+----------------+----------+-------------------------------+-----------+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+
        | zone1 | observer | 172.xx.xxx.xxx |     2882 | ob_storage_s3_url_encode_type | NULL      | default | Determines the URL encoding method for S3 requests."default": Uses the S3 standard URL encoding method."compliantRfc3986Encoding": Uses URL encoding that adheres to the RFC 3986 standard. | OBSERVER | CLUSTER | DEFAULT | DYNAMIC_EFFECTIVE |
        +-------+----------+----------------+----------+-------------------------------+-----------+---------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+----------+---------+---------+-------------------+
        1 row in set
        

     2. If the value is default, change it to compliantRfc3986Encoding.

        obclient> ALTER SYSTEM SET ob_storage_s3_url_encode_type='compliantRfc3986Encoding';
        

        For more information about this parameter, see ob_storage_s3_url_encode_type.

     3. Set the archive path and configure the cleanup mode of archive files with the delete_mode parameter.

        When you use COS as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant and sets the cleanup mode to delete. Example:

        obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test/backup/archive?host=cos.ap-xxxx.myqcloud.com&access_id=***&access_key=***&delete_mode=delete' TENANT = mysql_tenant;
        

        When you use COS as the archive medium, the user tenant sets the archive path for the current tenant and sets the cleanup mode to delete. Example:

        obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=s3://oceanbase-test/backup/archive?host=cos.ap-xxxx.myqcloud.com&access_id=***&access_key=***&delete_mode=delete';
        

        In the example, s3:// is used to access the archive path through the S3 protocol. The bucket name is oceanbase-test, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the host address of COS, which is the endpoint without the bucket name. access_id and access_key specify the access keys for COS, and the cleanup mode is delete.

        Notice

        During an archiving run, you cannot change the access protocol used for archiving. For example, you cannot switch from S3 to OSS or from OSS to S3.

     In OceanBase Database V4.2.5, Azure Blob is supported as an archive medium starting from V4.2.5 BP6.

     Like OSS, Azure Blob supports the delete_mode and checksum_type parameters. The delete_mode parameter configures the cleanup mode of archive files. If you do not explicitly set the delete_mode parameter, the default value is delete. The checksum_type parameter specifies the algorithm used to verify the integrity of archive files. Valid values are md5 and no_checksum. If you do not explicitly set the checksum_type parameter, the default value is md5.

     For more information about other parameters, see SET LOG_ARCHIVE_DEST.

     Examples:

     Notice

     • When you use object storage as the archive medium, the parameters in the object storage path are separated by the & symbol. Make sure that the parameter values contain only uppercase and lowercase English letters, digits, /-_$+=, and wildcards. If you enter other characters, the setting may fail.
     • When you use Azure Blob as the archive medium, the prefix of the host parameter must be http:// or https://. Because Azure Blob enables secure transfer by default, it is accessed through https:// by default. To access it through http://, you must disable the secure transfer option for Azure Blob. For more information, see Azure Blob documentation.

     • When you use Azure Blob as the archive medium, the sys tenant sets the archive path for the specified tenant mysql_tenant, sets the cleanup mode to delete, and specifies the verification algorithm as md5.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=azblob://oceanbase-test-bucket/backup/archive?host=http://****.blob.core.windows.net&access_id=****&access_key=****&delete_mode=delete&checksum_type=md5' TENANT = mysql_tenant;
       

     • When you use Azure Blob as the archive medium, the user tenant sets the archive path for the current tenant, sets the cleanup mode to delete, and specifies the verification algorithm as md5.

       obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=azblob://oceanbase-test-bucket/backup/archive?host=http://****.blob.core.windows.net&access_id=****&access_key=****&delete_mode=delete&checksum_type=md5';
       

     In the example, azblob:// indicates that Azure Blob is used as the archive medium. The bucket name is oceanbase-test-bucket, and the path in the bucket is /backup/archive. The ? character separates the path from the parameters, which are separated by &. host specifies the host address of the bucket, which can be obtained from the container properties or the storage account connection string. access_id specifies the storage account name. access_key specifies the access key for Azure Blob. The cleanup mode is delete, and the MD5 algorithm is used to verify the integrity of archive files.

   • Configure the BINDING attribute (optional)

     The BINDING attribute sets the priority mode between archiving and business operations. Currently, Optional mode and Mandatory mode are supported. If you do not set this attribute, the default value is Optional.

     • Optional mode means that business operations take priority. In this mode, if archiving cannot keep up with log generation, logs may be recycled before they are archived, which may cause log streaming interruption.

     • Mandatory mode means that archiving takes priority. In this mode, if archiving cannot keep up with data writes, writes may fail.

     When you use NFS as the archive medium, the sys tenant configures the archive path for the specified tenant mysql_tenant and sets the BINDING attribute. Example:

     obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive BINDING=Optional' TENANT = mysql_tenant;
     

     When you use NFS as the archive medium, the user tenant configures the archive path for the current tenant and sets the BINDING attribute. Example:

     obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive BINDING=Optional';
     

   • Configure the PIECE_SWITCH_INTERVAL attribute (optional)

     The PIECE_SWITCH_INTERVAL attribute configures the switch interval of a piece. The value range is [1d, 7d]. If you do not set this attribute, the default value is 1d.

     When you use NFS as the archive medium, the sys tenant configures the archive path for the specified tenant mysql_tenant and sets the log piece switch interval to one day. Example:

     obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive BINDING=Optional PIECE_SWITCH_INTERVAL=1d' TENANT = mysql_tenant;
     

     When you use NFS as the archive medium, the user tenant configures the archive path for the current tenant and sets the log piece switch interval to one day. Example:

     obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST='LOCATION=file:///data/nfs/backup/archive BINDING=Optional PIECE_SWITCH_INTERVAL=1d';
     

3. After the configuration is completed, you can query the parameter settings.

   You can query the CDB_OB_ARCHIVE_DEST view in the sys tenant and the DBA_OB_ARCHIVE_DEST view in a user tenant.

   For more information about how to view the archiving parameters, see View archiving parameters.

Considerations and instructions after configuration

After the LOG_ARCHIVE_DEST parameter is set, the system creates a format file in the destination directory by default. This file is used to verify the validity of the backup destination and ensure the integrity of the data in the destination. Therefore, when you configure the log archiving destination, note the following:

• If the format file does not exist, the destination directory must be empty for the configuration to be successful. Otherwise, the system will return an error -9080 indicating that the format file does not exist.

• If the format file already exists, its content must pass the validation for the configuration to be successful. Otherwise, the system will return an error -9081 indicating that the format file does not match. The content validation mainly checks whether the cluster, tenant, and backup destination type in the format file match the current cluster, tenant, and backup destination type.

• If the format file does not exist or the content validation fails, the backup task will fail.

After the archive destination is configured, incremental configuration is not supported. For example, if the BINDING attribute of the archive path /data/nfs/backup/archive under NFS is set to Mandatory and the PIECE_SWITCH_INTERVAL attribute is set to 1d, and you want to update the PIECE_SWITCH_INTERVAL attribute to 2d while keeping the BINDING attribute as Mandatory, you still need to specify the values of other attributes in the command. Otherwise, the unspecified attributes will use their default values.

You need to execute the following statements to make the changes.

• Modify the specified tenant in the sys tenant

  obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST = 'LOCATION=file:///data/nfs/backup/archive BINDING=Mandatory PIECE_SWITCH_INTERVAL=2d' TENANT = mysql_tenant;
  

• Modify the current tenant in the user tenant

  obclient> ALTER SYSTEM SET LOG_ARCHIVE_DEST = 'LOCATION=file:///data/nfs/backup/archive BINDING=Mandatory PIECE_SWITCH_INTERVAL=2d';
  

(Optional) Configure the archive lag target

OceanBase Database uses the tenant-level parameter archive_lag_target to control the delay in archiving logs for a tenant. This parameter supports units of milliseconds (ms), seconds (s), minutes (m), and hours (h), with a default value of 2 minutes. It specifies the maximum interval between two consecutive archive I/O operations, ensuring that online logs are archived in a timely manner to reduce the risk of data loss.

OceanBase Database archives logs in streams. If a log stream has logs being written and the time elapsed since the last archive of this stream exceeds the value specified by archive_lag_target, an archive operation is triggered for this stream, archiving all unarchived logs.

For example, if archive_lag_target is set to 120s (2 minutes), each log stream will attempt to perform an archive operation every 2 minutes (unless other conditions are met, such as the cache aggregation buffer for log archiving being full). This ensures that the interval between the current archive operation and the last one is less than 2 minutes. Note that when archive_lag_target is set to 0, real-time archiving is achieved.

For more information about the archive_lag_target parameter, see archive_lag_target.

Prerequisites

Before modifying the value of the archive_lag_target parameter, make sure that the archive destination has been configured. If no archive path is configured, the system will prompt log_archive_dest has not been set, set archive_lag_target is not allowed when you attempt to modify the parameter.

Considerations

• For scenarios where the archive medium is OSS or NFS, the value of archive_lag_target can be set to any value within its valid range. However, for scenarios where the archive medium is S3 or another object storage service that is compatible with the S3 protocol, the value of archive_lag_target must be at least 60s. If it is set to a value less than 60s, the system will return an error.

• It is recommended to set the value of archive_lag_target to a reasonable value to avoid excessive I/O operations that may impact system performance, especially when using object storage. Additionally, excessively high values may not meet the timeliness requirements for data recovery. Therefore, the value of archive_lag_target should be balanced based on specific business requirements and the performance of the archive medium.

Configuration method

1. Log in to the database as the sys tenant or the tenant administrator of a user tenant.

2. Choose a suitable statement to configure the archive lag based on your actual situation.

   Configuration methods:

   • The sys tenant configures the archive lag for a specified tenant

     obclient> ALTER SYSTEM SET archive_lag_target = '120s' TENANT = mysql_tenant;
     

   • The sys tenant configures the archive lag for all user tenants

     obclient> ALTER SYSTEM SET archive_lag_target = '120s' TENANT = all_user;
     

   • The user tenant configures the archive lag for the current tenant

     obclient> ALTER SYSTEM SET archive_lag_target = '120s';
     

References

• View archive parameters

• View archive progress

• View archive history