Common Issues

Last updated: 2020-02-20 12:31:13


Why can't I logically back up and download databases or tables in a sharding manner?

After the backup feature was upgraded, both logical and physical backup files adopt the new compression algorithm, so some download-related features may be unavailable for the time being. In this case, you can perform logical backup of databases or tables in a sharding manner by selecting Logical Backup > Specify Table in the manual backup feature and download the completed backup file.

Why does backup fail?

If the number of tables in a single instance exceeds one million, backup may fail, and database monitoring may be affected. Please control this value appropriately and make sure that it is below 1 million.

How to reduce backup costs?

  • Delete manual backups that are no longer used (you can do so in the console)
  • Reduce the frequency of automatic data backup for non-core businesses (you can reduce the number of days for backup in a week, which should be at least 2 days)
  • Shorten the retention period of data and log backups for non-core businesses (a retention period of 7 days can meet the needs in most cases)
Business Scenario Recommended Backup Retention Period
Core businesses 7-732 days
Non-core, non-data businesses 7 days
Archival businesses 7 days. It is recommended to manually back up data based on your actual business needs and delete the backups promptly after use
Testing businesses 7 days. It is recommended to manually back up data based on your actual business needs and delete the backups promptly after use

Can data and log backup be disabled in TencentDB for MySQL?


  • Data backups can be retained for 7-732 days. The option for reducing backup frequency will be available after backup becomes a paid service, so that you can reduce the capacity occupied by backup files.
  • Log backups can be retained for 7-732 days and the retention period cannot be longer than that of data backups.

    Currently, backup capacity used is free of charge. If fees will be charged, we will inform you in advance. Please develop a backup schedule and plan the backup capacity appropriately to avoid potential extra fees in the future.

Why cannot a downloaded backup file be decompressed/unpacked with tar?

Given that backup files in the new version adopt a new compression algorithm, they cannot be unpacked/decompressed using the original tar tool; instead, xbstream and qpress are required.

  1. The downloaded backup file should be unpacked with xbstream (a packing/unpacking tool offered by Percona) first.
    xbstream -x < test_import_57_backup_20181114115236.xb 
    Then, a .qb file can be obtained, such as test_import_57_backup_20181114115236.sql.qb.
  2. The .qb file needs to be decompressed with qpress.
    qpress -d test_import_57_backup_20181114115236.sql.qp
    Then, the complete backup file can be obtained, such as test_import_57_backup_20181114115236.sql.

How to download xbstream and qpress?

  • xbstream is a subprogram of Percona XtraBackup. Before using it, you need to install Percona XtraBackup with yum or binary installation package.
  • Download qpress here and extract the qpress binary files by running the tar command:
    For more information on installation of xtrabackup and qpress, see Restoring a Database from a Physical Backup File.

How to manually set up MySQL backup?

You can back up your MySQL data by offline migrating the data to the local file system. For more information, see Migrating Data Offline.

How to back up data on my own?

TencentDB for MySQL instances are fully backed up on a daily basis. You can also proactively back up your data using the multi-threaded quick import/export tool provided by TencentDB or using mysqldump. For more information, see Backup Methods.

How to view binlogs in MySQL?

  • Download the binlogs from the console to the local file system such as a CVM instance.
  • View them using mysqlbinlog. To do so, mysqlbinlog v3.4 or higher is required in MySQL v5.6.

How to achieve sync of real-time data in two TencentDB for MySQL instances in a local dual-backup architecture?

For this purpose, you can purchase disaster recovery instances in the TencentDB for MySQL Console.