Reduced Disk Space Standby
First Claim
1. A computer-implemented method, comprising:
- a main standby database system applying changes to standby database files that were received from a primary database system;
in response to applying changes, advancing an established logical time for computing queries to a particular logical time;
sending to one or more subsidiary standby database systems said particular logical time, wherein said one or more subsidiary standby database systems do not apply said changes to said standby database files; and
while said standby database system is applying said changes to said standby database files;
receiving a query issued to a subsidiary standby database system of the one or more subsidiary database systems; and
said subsidiary standby database system computing results for said query that are consistent with said particular logical time based on data read from said standby database files;
wherein each of the above steps is performed by one or more computing devices.
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Accused Products
Abstract
A method and system for replicating database data is provided. One or more standby database replicas can be used for servicing read-only queries, and the amount of storage required is scalable in the size of the primary database storage. One technique is described for combining physical database replication to multiple physical databases residing within a common storage system that performs de-duplication. Having multiple physical databases allows for many read-only queries to be processed, and the de-duplicating storage system provides scalability in the size of the primary database storage. Another technique uses one or more diskless standby database systems that share a read-only copy of physical standby database files. Notification messages provide consistency between each diskless system'"'"'s in-memory cache and the state of the shared database files. Use of a transaction sequence number ensures that each database system only accesses versions of data blocks that are consistent with a transaction checkpoint.
41 Citations
7 Claims
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1. A computer-implemented method, comprising:
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a main standby database system applying changes to standby database files that were received from a primary database system; in response to applying changes, advancing an established logical time for computing queries to a particular logical time; sending to one or more subsidiary standby database systems said particular logical time, wherein said one or more subsidiary standby database systems do not apply said changes to said standby database files; and while said standby database system is applying said changes to said standby database files; receiving a query issued to a subsidiary standby database system of the one or more subsidiary database systems; and said subsidiary standby database system computing results for said query that are consistent with said particular logical time based on data read from said standby database files; wherein each of the above steps is performed by one or more computing devices. - View Dependent Claims (2, 3, 4, 5)
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6. A method comprising:
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a plurality of standby database systems applying changes to distinct copies of standby database files that were received from a primary database system; wherein said each distinct copy of standby database files is managed by a corresponding standby database system of the plurality of standby database systems; wherein each distinct copy of standby database files is stored in a persistent storage system that stores said each distinct copy of standby database files using de-duplication; and wherein using de-duplication causes replacing a set of data blocks having identical content, said data blocks contained in at least two of the plurality of physical standby databases, with one data block in the persistent storage system, wherein the one data block contains said identical content; wherein each of the above steps is performed by one or more computing devices.
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7. A computer-implemented method, comprising:
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in response to a main standby database system applying changes to standby database files, one or more subsidiary database systems receiving a notification message from said standby database system; in response to receiving the notification message, said one or more subsidiary database systems managing an in-memory cache to be consistent with said standby database files based on information in the notification message; and said one or more subsidiary database system responding to read-only queries with transactionally consistent data.
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Specification