Self-adaptive copy retention management

A system for managing copy retention for backups of a database, the system comprising:

• a processor;
• and memory configured to store one or more sequences of instructions which, when executed by the processor, cause the processor to carry out the steps of:
• identifying a current retention mode as being one of a conservative mode or an aggressive mode, wherein the conservative mode preserves expired backup copies on which an unexpired backup depends, and the aggressive mode deletes the expired backup copies on which the unexpired backup copy depends when a plurality of conditions are satisfied;
• when the current retention mode is identified as the aggressive mode, checking whether used space on backup storage is below a lower threshold;
• when the used space is below the lower threshold, switching into the conservative mode;
• when the used space is above the lower threshold, remaining in the aggressive mode;
• and
• while in the aggressive mode, selecting a backup chain of the database for pruning, the selected backup chain having a shortest retention term of all backup chains of the database not yet pruned, and not being a latest backup chain of all the backup chains;
• identifying log backups of the database in the selected backup chain, the log backups comprising a log file of transactions issued by a client, the transactions having been written from memory to the log file and then committed to the database;
• and
• deleting each log backup of the database in the selected backup chain that has expired regardless of dependency of other backups on an expired log backup.

A computer program product, comprising a non-transitory computer-readable medium having a computer-readable program code embodied therein, the computer-readable program code adapted to be executed by one or more processors to implement a method for managing copy retention for backups of a database, the method comprising:

• identifying a current retention mode as being one of a conservative mode or an aggressive mode, wherein the conservative mode preserves expired backup copies on which an unexpired backup copy depends, and the aggressive mode deletes the expired backup copies on which the unexpired backup copy depends when a plurality of conditions are satisfied;
• when the current retention mode is identified as the aggressive mode, checking whether used space on backup storage is below a lower threshold;
• when the used space is below the lower threshold, switching into the conservative mode;
• when the used space is above the lower threshold, remaining in the aggressive mode;
• and
• while in the aggressive mode, selecting a backup chain of the database for pruning, the selected backup chain having a shortest retention term of all backup chains of the database not yet pruned, and not being a latest backup chain of all the backup chains;
• identifying log backups of the database in the selected backup chain, the log backups comprising a log file of transactions issued by a client, the transactions having been written from memory to the log file and then committed to the database;
• and
• deleting each log backup of the database in the selected backup chain that has expired regardless of dependency of other backups on an expired log backup.