Method and apparatus providing system availability during DBMS restart recovery

Claim 1

A method for providing system availability during recovery of a database, comprising: performing abbreviated UNDO processing of objects in a database such that new transactions are not accepted, the abbreviated UNDO recovery processing comprising: receiving user-supplied thesholds including a number of log records to process during UNDO recovery processing; determining whether a log record entry represents a first undoable update made by a transaction to an object to which the log record applies, and if the log record represents the transaction's first update to the object; and designating a corresponding interest entry as complete, thereby indicating that the transaction has no further UNDO recovery processing required for that object; restricting an object from transaction access based upon selected criteria, wherein unrestricted objects remain available for transaction access; accepting new transactions; maintaining an interest list, the interest list used to track objects affected by a transaction; making entries to the interest list accessible during recovery processing; waiting until REDO recovery processing, if any, has completed before performing abbreviated UNDO recovery processing; restricting an object from transaction access including: restricting any object reference in the interest list from transaction access based upon the selected criteria, wherein unrestricted objects remain available for transaction access; and restricting transaction access to an interest list entry's object if there remains a transaction with update interest in the object and UNDO recovery processing has not been completed on that object; performing further UNDO recovery processing by: determining whether a log record entry represents a first undoable update made by a transaction to an object; if the log record represents the transaction's first update to the object, designating a corresponding interest list entry as complete, complete indicating that the transaction has no further UNDO processing required for that object; and removing an object's restriction if UNDO work against the object has been completed; and copying the interest list to a log at a system check-point time.

Claim 2

A method for providing system availability during recovery of a database, comprising: performing abbreviated UNDO processing of objects in a database such that new transactions are not accepted, the abbreviated UNDO recovery processing comprising: receiving user-supplied thesholds including a number of log records to process during UNDO recovery processing; determining whether a log record entry represents a first undoable update made by a transaction to an object to which the log record applies, and if the log record represents the transaction's first update to the object; and designating a corresponding interest entry as complete, thereby indicating that the transaction has no further UNDO recovery processing required for that object; restricting an object from transaction access based upon selected criteria, wherein unrestricted objects remain available for transaction access; accepting new transactions; maintaining an interest list, the interest list used to track objects affected by a transaction; making entries to the interest list accessible during recovery processing; waiting until REDO recovery processing, if any, has completed before performing abbreviated UNDO recovery processing; restricting an object from transaction access including: restricting any object reference in the interest list from transaction access based upon the selected criteria, wherein unrestricted objects remain available for transaction access; and restricting transaction access to an interest list entry's object if there remains a transaction with update interest in the object and UNDO recovery processing has not been completed on that object; performing further UNDO recovery processing by: determining whether a log record entry represents a first undoable update made by a transaction to an object; if the log record represents the transaction's first update to the object, designating a corresponding interest list entry as complete, complete indicating that the transaction has no further UNDO processing required for that object; and removing an object's restriction if UNDO work against the object has been completed; and copying the interest list to a log at a system check-point time.

Claim 17

An apparatus used to provide system availability during recovery of a database, the apparatus comprising: non-volatile storage; memory; a processor, the processor executing commands to recover the database while providing system available by: maintaining an interest list, the interest list used to track objects affected by a transaction; making entries to the interest list accessible during recovery processing; waiting until REDO recovery processing, if any, has completed; performing abbreviated UNDO recovery processing such that new transactions are not accepted the abbreviated UNDO recovery processing comprising: receiving user-supplied thresholds including a number of log records to process during UNDO recovery processing; determining whether a log record entry represents a first undoable update made by a transaction to an object to which the log record applies, and if the log record represent the transaction's first update to the object; and designating a corresponding interest entry as complete, thereby indicating that the transaction has no further UNDO recovery processing required for that object; restricting any object referenced in the interest list from transaction access based upon the selected criteria wherein the selected criteria comprises restricting transaction access to an interest list entry's object if there remains a transaction with update interest in the object and UNDO recovery processing has not been completed on that object; accepting new transactions; and performing further UNDO recovery processing, including; determining whether a log record entry represents a first undoable update made by a transaction to an object; if the log record represents the transaction's first update to the object, designating a corresponding interest list entry as complete, complete indicating that the transaction has no further UNDO processing required for that object; removing an object's restriction if UNDO work against the object has been completed; and copying the interest list to a log at a system check-point time.

Claim 18

An apparatus used to provide system availability during recovery of a database, the apparatus comprising: non-volatile storage; memory; a processor, the processor executing commands to recover the database while providing system available by: maintaining an interest list, the interest list used to track objects affected by a transaction; making entries to the interest list accessible during recovery processing; waiting until REDO recovery processing, if any, has completed; performing abbreviated UNDO recovery processing such that new transactions are not accepted the abbreviated UNDO recovery processing comprising: receiving user-supplied thresholds including a number of log records to process during UNDO recovery processing; determining whether a log record entry represents a first undoable update made by a transaction to an object to which the log record applies, and if the log record represent the transaction's first update to the object; and designating a corresponding interest entry as complete, thereby indicating that the transaction has no further UNDO recovery processing required for that object; restricting any object referenced in the interest list from transaction access based upon the selected criteria wherein the selected criteria comprises restricting transaction access to an interest list entry's object if there remains a transaction with update interest in the object and UNDO recovery processing has not been completed on that object; accepting new transactions; and performing further UNDO recovery processing, including; determining whether a log record entry represents a first undoable update made by a transaction to an object; if the log record represents the transaction's first update to the object, designating a corresponding interest list entry as complete, complete indicating that the transaction has no further UNDO processing required for that object; removing an object's restriction if UNDO work against the object has been completed; and copying the interest list to a log at a system check-point time.