Change tracking
AssigneeEMC Corporation
InventorsMilena Bergant, Matthew C. McCline, Alon Goldshuv
Life of this patent
Estimating the term…
Abstract
A method, article of manufacture, and apparatus for recovering databases. In some embodiments, this includes switching an active segment to change tracking mode, intercepting write related changes on the active segment while in the change tracking mode, populating a change tracking log based on the intercepted write related changes, and storing the populated change tracking log in a storage device. In some embodiments, the storage device is memory. In some embodiments, the change tracking log if flushed from memory to disk.
Claims7
A method for recovering a database, comprising:
- switching an active segment to change tracking mode;
- intercepting a write related change on the active segment while in the change tracking mode;
- populating a change tracking log with records based on the intercepted write related change, wherein the records are associated with a log sequence number;
- identifying a block associated with the write related change;
- determining, based on a policy, whether the populated change tracking log contains an old entry related to the block;
- removing the old entry without making write related changes dictated by the old entry based on the policy, wherein the policy dictates that if when multiple records exist for a given data block, only the record with the largest log sequence number is retained and wherein the identifying, the determining, and the removing occur based on a policy trigger;
- and
- storing the populated change tracking log in a storage device.
A system for processing recovering a database, comprising a storage device and hardware processor configured to:
- switching an active segment to change tracking mode;
- intercepting a write related changes on the active segment while in the change tracking mode;
- populating a change tracking log with records based on the intercepted write related changes, wherein the records are associated with a log sequence number;
- identifying a block associated with the write related change;
- determining, based on a policy, whether the populated change tracking log contains an old entry related to the block;
- removing the old entry without making write related changes dictated by the old entry based on the policy, wherein the policy dictates that if multiple records exist for a given data block, only the record with the largest log sequence number is retained and wherein the identifying, the determining, and the removing occur based on a policy trigger;
- and
- storing the populated change tracking log in the storage device.
A computer program product for recovering databases, comprising a non-transitory computer readable medium having program instructions embodied therein for:
- switching an active segment to change tracking mode;
- intercepting a write related change on the active segment while in the change tracking mode;
- populating a change tracking log with records based on the intercepted write related change, wherein the records are associated with a log sequence number;
- identifying a block associated with the write related change;
- determining, based on a policy, whether the populated change tracking log contains an old entry related to the block;
- removing the old entry without making write related changes dictated by the old entry based on the policy, wherein the policy dictates that if multiple records exist for a given data block, only the record with the largest log sequence number is retained and wherein the identifying, the determining, and the removing occur based on a policy trigger;
- and
- storing the populated change tracking log in a storage device.
Dependencies are inferred from the claim text.