Reduced disk space standby
First Claim
1. A computer-implemented method, comprising:
- a main standby database system applying changes to standby database files, wherein the changes were made to a primary database of a primary database system;
in response to applying changes, advancing an established logical time associated with a consistent state of the primary database system for computing queries to a particular logical time associated with a subsequent consistent state of the primary database system;
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 main 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.
82 Citations
10 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, wherein the changes were made to a primary database of a primary database system; in response to applying changes, advancing an established logical time associated with a consistent state of the primary database system for computing queries to a particular logical time associated with a subsequent consistent state of the primary database system; 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 main 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 non-transitory computer-readable medium storing one or more sequences of instructions which, when executed by one or more processors, cause performing of:
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a main standby database system applying changes to standby database files, wherein the changes were made to a primary database of a primary database system; in response to applying changes, advancing an established logical time associated with a consistent state of the primary database system for computing queries to a particular logical time associated with a subsequent consistent state of the primary database system; 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 main 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. - View Dependent Claims (7, 8, 9, 10)
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Specification