Asynchronous Garbage Collection In Database Redo Log Replay

A system comprising:

• at least one data processor;
• and
• memory storing instructions which, when executed by the at least one data processor, result in operations comprising:
• initiating replication of a primary database system by having an associated secondary database system mirroring data stored in the primary database system and sending a most recent savepoint of the primary database system to the secondary database system;
• replaying, by the secondary database system, recovery operations specified by a redo log of the primary database system and sent to the secondary database system;
• initiating, concurrent to subsequent recovery operations, garbage collection of cleanup operations which are part of the savepoint sent from the primary database system;
• generating, by the secondary database system, a cleanup log identifying cleanup operations occurring during the replay of the recovery operations for garbage collection;
• initiating, by the secondary database system concurrent with the replay of the recovery operations and the garbage collection specified by the database savepoint, garbage collection of the cleanup operations;
• and
• redirecting readonly transactions for execution by the primary database system to the secondary database system which are able to block the asynchronous garbage collection in the secondary database system to get a stable view of data replicated on the secondary database system as required by certain transaction isolation levels.

A system comprising:

• means for initiating recovery of a database system by taking the database system offline;
• means for replaying recovery operations specified by a redo log of the database system;
• means for generating a cleanup log identifying cleanup operations occurring during the replay of the recovery operations for garbage collection;
• means for initiating, concurrent with the startup of the database, garbage collection of the cleanup operations as specified in a last database savepoint;
• means for initiating, concurrent with the replay of the recovery operations and the garbage collection specified by the database savepoint, garbage collection of the cleanup operations specified by the cleanup log;
• and
• means for bringing the database system online after all of the recovery operations are replayed.