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    PolarDB:Enable binary logging

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    PolarDB:Enable binary logging

    Last Updated:Feb 28, 2026

    PolarDB for MySQL uses redo logs, which are more advanced than binary logs. Binary logging is disabled by default. Enable it when you need MySQL ecosystem compatibility, for example, to replicate data through Data Transmission Service (DTS), stream changes to Elasticsearch or AnalyticDB, or synchronize data across clusters.

    Use cases

    Limits

    Clusters created before April 5, 2019 must update to the latest minor version before enabling binary logging. For details, see Revision version management. Clusters created on or after that date support binary logging directly.

    Billing

    Binary logs consume cluster storage space, charged at your cluster's storage rate.

    Storage billing method Billing behavior
    Subscription No additional fees as long as total storage stays within your purchased capacity
    Pay-as-you-go Charged based on the actual storage occupied by binary log data

    Performance impact

    Binary logging affects write operations (INSERT, UPDATE, DELETE) only -- read performance is unaffected. The typical impact is within 10%, but can reach 40% under extreme workloads.

    Large transaction commits can block other transactions and extend restart or configuration change duration.

    Enable binary logging

    Enable during cluster creation

    Select Enable in the Enable Binary Logging section when creating a cluster. For details, see Custom purchase or Purchase a subscription cluster.

    Enable for an existing cluster

    Important

    Enabling binary logging triggers an automatic cluster restart that typically takes 5 to 15 minutes, with a service interruption of approximately 40 seconds. Recovery time varies based on data volume and table count. Perform this operation during off-peak hours and make sure your application supports automatic reconnection.

    Method 1: Use the Binary Logs page

    1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster and click its ID to go to the Basic Information page.

    2. In the left-side navigation pane, click Binary Logs.

    3. Click Enable Now.

    4. In the Enable Binary Logging dialog box, set the Effective Mode parameter to Now or Scheduled. If you select Scheduled, specify when to enable binary logging.

    5. Click OK.

    Method 2: Set the loose_polar_log_bin parameter

    1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster and click its ID to go to the Basic Information page.

    2. In the left-side navigation pane, choose Settings and Management > Parameters.

    3. Find the loose_polar_log_bin parameter and change its value. For details, see the "Modify parameters" section of Configure cluster and node parameters.

      MySQL version Parameter value
      MySQL 5.6 ON_WITH_GTID
      MySQL 5.7 or 8.0 ON

    Disable binary logging

    Method 1: Use the Binary Logs page

    1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster and click its ID to go to the Basic Information page.

    2. In the left-side navigation pane, click Binary Logs.

    3. Click Disable Binary Logging.

    4. In the Disable Binary Logging dialog box, set the Effective Mode parameter to Now or Scheduled. If you select Scheduled, specify when to disable binary logging. Optionally, select Clear Local Binary Logs.

    5. Click OK.

    Method 2: Set the loose_polar_log_bin parameter

    1. Log on to the PolarDB console. In the left-side navigation pane, click Clusters. In the upper-left corner, select the region of the cluster. In the cluster list, find the cluster and click its ID to go to the Basic Information page.

    2. In the left-side navigation pane, choose Settings and Management > Parameters.

    3. Find the loose_polar_log_bin parameter and change its value. For details, see Configure cluster and node parameters.

      MySQL version Parameter value
      MySQL 5.6 OFF_WITH_GTID
      MySQL 5.7 or 8.0 OFF
    Note

    After you disable binary logging, existing binary log files are permanently retained. To free storage space, shorten the retention period before disabling the feature. Wait for older logs to be automatically purged, then disable binary logging.

    Binary log retention

    Retention policies

    Condition Default retention
    Binary logging enabled 3 days
    Binary logging disabled Existing files retained permanently

    Binary log files are automatically deleted after the retention period expires.

    Note

    • For a PolarDB for MySQL cluster that was purchased before November 23, 2023, binary log files are retained for two weeks (14 days) by default.

    • For a PolarDB for MySQL cluster that was purchased before January 17, 2024, binary log files are retained for one week (seven days) by default.

    Modify the retention period

    Important

    • Changing the retention period does not disrupt connections or require a cluster restart.

    • If a large volume of binary logs (such as 10 TB) needs to be purged, brief write operation exceptions may occur. In this case, change the retention period during off-peak hours. Alternatively, shorten the period progressively so that only a portion of logs is cleared at a time.

    • Deleted binary log files cannot be restored.

    Modify one of the following parameters based on your MySQL version:

    MySQL version Parameter Valid values Unit Default
    5.6 loose_expire_logs_hours 0-2376 Hours 72
    5.7 or 8.0 binlog_expire_logs_seconds 0-4294967295 Seconds 259200 (3 days)

    A value of 0 means binary log files are never automatically deleted.

    For instructions on modifying parameters, see Configure cluster and node parameters.

    Trigger immediate purging

    After changing the retention parameter, historical logs are not immediately cleared. Use one of these methods to trigger purging:

    • Wait for the active binary log file to reach the size set by max_binlog_size. When it rotates, all expired files are automatically deleted.

    • Run flush binary logs with the privileged account.

    • Restart the cluster.

    Delete binary logs when binary logging is disabled

    If binary logging is disabled and you want to remove accumulated log files:

    1. Re-enable binary logging. See Enable binary logging.

    2. Set loose_expire_logs_hours or binlog_expire_logs_seconds to a smaller value.

    3. Wait for expired logs to be automatically purged.

    4. Disable binary logging again.

    View and parse binary logs

    Use the mysqlbinlog tool to retrieve and parse binary logs remotely. For details, see Remotely obtain and parse the binary log files of a PolarDB for MySQL cluster.

    To check the last write time of each binary log file, run:

    show full binary logs;

    This returns the file name, size, and last write time for each binary log file.

    Note

    show full binary logs requires one of the following minimum revision versions:

    • MySQL 8.0.2: revision 8.0.2.2.0 or later

    • MySQL 8.0.1: revision 8.0.1.1.14 or later

    • MySQL 5.7: revision 5.7.1.0.27 or later

    • MySQL 5.6: revision 5.6.1.0.38 or later

    Usage notes

    • Use the primary endpoint: When consuming binary logs through DTS or other services, connect to the Primary Endpoint of your cluster. This endpoint always points to the primary node that generates binary logs. To find the primary endpoint, see the "View the endpoint and port" section of Manage the endpoints of a cluster.

    • Global vs. session-level logging: The loose_polar_log_bin parameter controls binary logging at the global level. For session-level control, use the sql_log_bin parameter (disabled by default). To enable sql_log_bin, go to Quota Center, find the polardb SQL_log_bin parameter permissions quota, and click Apply in the Actions column.

    • Automatic enablement during migration: DTS automatically enables binary logging when migrating data from an ApsaraDB RDS instance to a PolarDB cluster.

    FAQ

    What does Could not find first log file name in binary log index file mean?

    The binary log file has been deleted. Deleted files cannot be restored.

    Can I use Canal for change data capture?

    Yes. After enabling binary logging, Canal can capture changes from your PolarDB for MySQL cluster.

    Why can't I perform lock-free DDL operations in DMS?

    Lock-free DDL operations in Data Management Service (DMS) require binary logging to be enabled. If you do not want to enable it, use online DDL instead.

    Does SHOW BINARY LOGS affect cluster performance?

    No. This is a metadata query that does not write data. It has no measurable impact on read or write performance.

    How do I view binary logs generated at a specific point in time?

    Restore data to that point in time, then parse the binary logs from the restored instance. For details, see Database and table restoration: Restore data to an earlier point in time.