Methods and apparatus for optimizing undo log usage
First Claim
Patent Images
1. A data processing recovery apparatus comprising:
- a redo buffer containing a set of redo records, said redo buffer including information for committed and uncommitted transactions;
an undo buffer containing a set of undo records, said undo buffer including information only for an uncommitted transaction, said undo records being aggregated in said undo buffer separately from said redo records in said redo buffer; and
a log management routine for starting an uncommitted transaction, recording redo records corresponding to said uncommitted transaction in said redo buffer, recording undo records for said uncommitted transaction in said undo buffer, committing said transaction, storing said redo records corresponding to said committed transaction from said redo buffer to persistent storage, and for separately discarding said undo records corresponding to said committed transaction from said undo buffer while retaining said redo records in said redo buffer.
4 Assignments
0 Petitions
Accused Products
Abstract
Each node in a data processing system contains at least one undo buffer and one least one redo buffer for insuring that any changes made to a section of a non-volatile storage medium, such as a disk, can be removed, if a transaction has not been committed, or can be recreated if the transaction has not been committed. The undo buffers each correspond to a different uncommitted transaction. The redo buffer contains the changes made to a copy of the section which is maintained in the memory.
241 Citations
7 Claims
-
1. A data processing recovery apparatus comprising:
-
a redo buffer containing a set of redo records, said redo buffer including information for committed and uncommitted transactions; an undo buffer containing a set of undo records, said undo buffer including information only for an uncommitted transaction, said undo records being aggregated in said undo buffer separately from said redo records in said redo buffer; and a log management routine for starting an uncommitted transaction, recording redo records corresponding to said uncommitted transaction in said redo buffer, recording undo records for said uncommitted transaction in said undo buffer, committing said transaction, storing said redo records corresponding to said committed transaction from said redo buffer to persistent storage, and for separately discarding said undo records corresponding to said committed transaction from said undo buffer while retaining said redo records in said redo buffer. - View Dependent Claims (2, 3, 4)
-
-
5. A method for data processing recovery comprising the steps of:
-
providing a redo buffer containing a set of redo records, said redo buffer including information for committed and uncommitted transactions; providing an undo buffer containing a set of undo records, said undo buffer including information only for an uncommitted transaction, said undo records being aggregated in said undo buffer separately from said redo records in said redo buffer; starting an uncommitted transaction; recording redo records corresponding to said uncommitted transaction in said redo buffer; recording undo records for said uncommitted transaction in said undo buffer; committing said transaction; storing said redo records corresponding to said committed transaction from said redo buffer to persistent storage; and separately discarding said undo records corresponding to said committed transaction from said undo buffer while retaining said redo records in said redo buffer. - View Dependent Claims (6, 7)
-
Specification