Buffered message queue architecture for database management systems with guaranteed at least once delivery
First Claim
1. A method for managing messages in a database system, the method comprising the computer-implemented step of in response to a first message in a message queue created in a volatile memory of the database system being provided to all subscriber processes for which the first message satisfies the corresponding subscription data, generating a checkpoint value that indicates that the first message does not need to be restored to the message queue after a failure that causes the loss of the first message from the message queue;
- and storing the checkpoint value on a non-volatile storage.
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Abstract
A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained. Messages published to the buffered message queue are delivered to all eligible subscribers at least once, even in the event of failures, as long as the application is “repeatable.” The buffered message queue architecture also includes management mechanisms for performing buffered message queue cleanup and also for providing unlimited size buffered message queues when limited amounts of shared memory are available. The architecture also includes “zero copy” buffered message queues and provides for transaction-based enqueue of messages.
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Citations
30 Claims
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1. A method for managing messages in a database system, the method comprising the computer-implemented step of in response to a first message in a message queue created in a volatile memory of the database system being provided to all subscriber processes for which the first message satisfies the corresponding subscription data,
generating a checkpoint value that indicates that the first message does not need to be restored to the message queue after a failure that causes the loss of the first message from the message queue; - and
storing the checkpoint value on a non-volatile storage. - View Dependent Claims (2, 3)
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4. A method for managing messages in a database system, the method comprising the computer-implemented steps of:
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generating and storing on a non-volatile storage in the database system, a first checkpoint value that identifies a first most recent message that was enqueued by a first publisher into a message queue implemented in a volatile memory of the database system and dequeued by all subscribers to the message queue for which the first most recent message satisfies corresponding subscription data; and
generating and storing on the non-volatile storage a second checkpoint value that identifies a second most recent message that was enqueued by a second publisher into the message queue and dequeued by all subscribers to the message queue for which the second most recent message satisfies the corresponding subscription data. - View Dependent Claims (5, 6)
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7. A method for managing messages in a distributed database environment, the method comprising the computer-implemented steps of:
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propagating one or more messages from a first message queue disposed in a volatile memory of a first database system to a second message queue disposed in a volatile memory of a second database system; and
receiving and storing in a non-volatile memory at the first database system, propagation acknowledgement data that indicates a most recent message from the one or more messages that have been processed for all subscribers to the second message queue of the second database system. - View Dependent Claims (8, 9, 10)
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11. A computer-readable medium for managing messages in a database system, the computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the step in response to a first message in a message queue created in a volatile memory of the database system being provided to all subscriber processes for which the first message satisfies the corresponding subscription data,
generating a checkpoint value that indicates that the first message does not need to be restored to the message queue after a failure that causes the loss of the first message from the message queue; - and
storing the checkpoint value on a non-volatile storage. - View Dependent Claims (12, 13)
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14. A computer-readable medium for managing messages in a database system, the computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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generating and storing on a non-volatile storage in the database system, a first checkpoint value that identifies a first most recent message that was enqueued by a first publisher into a message queue implemented in a volatile memory of the database system and dequeued by all subscribers to the message queue for which the first most recent message satisfies corresponding subscription data; and
generating and storing on the non-volatile storage a second checkpoint value that identifies a second most recent message that was enqueued by a second publisher into the message queue and dequeued by all subscribers to the message queue for which the second most recent message satisfies the corresponding subscription data. - View Dependent Claims (15, 16)
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17. A computer-readable medium for managing messages in a distributed database environment, the computer-readable medium carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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propagating one or more messages from a first message queue disposed in a volatile memory of a first database system to a second message queue disposed in a volatile memory of a second database system; and
receiving and storing in a non-volatile memory at the first database system, propagation acknowledgement data that indicates a most recent message from the one or more messages that have been processed for all subscribers to the second message queue of the second database system. - View Dependent Claims (18, 19, 20)
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21. An apparatus for managing messages in a database system, the apparatus comprising a memory carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the step in response to a first message in a message queue created in a volatile memory of the database system being provided to all subscriber processes for which the first message satisfies the corresponding subscription data,
generating a checkpoint value that indicates that the first message does not need to be restored to the message queue after a failure that causes the loss of the first message from the message queue; - and
storing the checkpoint value on a non-volatile storage. - View Dependent Claims (22, 23)
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24. An apparatus for managing messages in a database system, the apparatus comprising a memory carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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generating and storing on a non-volatile storage in the database system, a first checkpoint value that identifies a first most recent message that was enqueued by a first publisher into a message queue implemented in a volatile memory of the database system and dequeued by all subscribers to the message queue for which the first most recent message satisfies corresponding subscription data; and
generating and storing on the non-volatile storage a second checkpoint value that identifies a second most recent message that was enqueued by a second publisher into the message queue and dequeued by all subscribers to the message queue for which the second most recent message satisfies the corresponding subscription data. - View Dependent Claims (25, 26)
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27. An apparatus for managing messages in a distributed database environment, the apparatus comprising a memory carrying one or more sequences of instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
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propagating one or more messages from a first message queue disposed in a volatile memory of a first database system to a second message queue disposed in a volatile memory of a second database system; and
receiving and storing in a non-volatile memory at the first database system, propagation acknowledgement data that indicates a most recent message from the one or more messages that have been processed for all subscribers to the second message queue of the second database system. - View Dependent Claims (28, 29, 30)
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Specification