System and method for assuring atomicity of distributed update requests in a parallel database

Claim 3

A method of managing distributed requests on a parallel database management system as set forth in claim 1, and further comprising: responsive to initiation of a transaction, initializing a request counter for the coordination process; responsive to receipt of a request from an application program by the coordination process, incrementing the request counter for the coordination process; and the step of distributing including passing the request counter as request savepoint data.

Claim 4

A method of managing distributed requests on a parallel database management system as set forth in claim 2, wherein locally generated savepoint data includes a log sequence number tracking instances of changes to a partition.

Claim 5

A method of managing distributed requests on a parallel database management system as set forth in claim 3, and further comprising: responsive to initiation of a transaction, initializing the local savepoint for all of a plurality of distributed processes by setting the local request counter and the log sequence number to value indicating no prior issuance of request savepoint data.

Claim 6

A method of managing distributed requests on a parallel database management system as set forth in claim 4, wherein updating of a local savepoint further includes adding a current value for the log sequence number to the savepoint.

Claim 7

A method of managing distributed requests on a parallel database management system as set forth in claim 5, and further comprising: responsive to issuance of a request instance to a selected subordinate process, discarding any prior savepoint for the selected subordinate processes; responsive to rolling back to a savepoint on a subordinate process, discarding the savepoint; and responsive to conclusion of the transaction, discarding savepoints across all subordinate processes.

Claim 8

A parallel database management system for managing distributed requests which each comprise a plurality of request instances which may span a plurality of subordinate processes, comprising: a network having a plurality of computers; a database distributed among partitions on the plurality of computers; a plurality of subordinate processes resident on the plurality of computers for generating local savepoints for the partitions, for executing a request instance and for signalling over the network failure or success of execution; a coordinator resident on a computer for receiving requests from applications wherein each request comprises a plurality of request instances, for distributing request instances and request savepoint data relating to the request to selected subordinate processes and for issuing a rollback request with a reference for comparison to the local savepoints upon receipt of a signal indicating failure of execution by a subordinate process; memory for each of the plurality of computers for storing the local savepoints between the requests; and the subordinate processes being responsive to the reference of the matching the local savepoints for executing a rollback.

Claim 9

A parallel database management system for managing distributed requests which each comprise a plurality of request instances which may span a plurality of subordinate processes, comprising: a network having a plurality of computers; a database distributed among partitions on the plurality of computers; a plurality of subordinate processes resident on the plurality of computers for generating local savepoints for the partitions, for executing a request instance and for signalling over the network failure or success of execution; a coordinator resident on a computer for receiving requests from applications wherein each request comprises a plurality of request instances, for distributing request instances and request savepoint data relating to the request to selected subordinate processes and for issuing a rollback request with a reference for comparison to the local savepoints upon receipt of a signal indicating failure of execution by a subordinate process; memory for each of the plurality of computers for storing the local savepoints between the requests; and the subordinate processes being responsive to the reference of the matching the local savepoints for executing a rollback.

Claim 10

A parallel database management system for managing distributed requests as set forth in claim 7, and further comprising: a log sequence number generator for each computer for tracking all changes to the partition during a transaction; and means with each computer responsive to receipt of a request instance for placing a log sequence number into the local savepoint.

Claim 11

A parallel database management system for managing distributed requests as set forth in claim 8, wherein the request savepoint data includes a value for the request count for the coordinator.

Claim 12

A parallel database management system for managing distributed requests as set forth in claim 9, the coordinator further including a process responsive to entry to a transaction for initiating a request counter for the coordinator.

Claim 13

A parallel database management system for managing distributed requests as set forth in claim 10, the subordinate processes further including a process responsive to entry to a transaction for initiating a request counter for each subordinate process and for initiating the log sequence count.

Claim 14

A data processing program product for assuring atomicity of distributed update requests on a parallel database management system wherein each distributed update request comprises a plurality of request instances which may span a plurality of subordinate processes, said data processing program product comprising media storing: instruction means for distributing a plurality of request instances for a selected request to a plurality of subordinate processes, each request instance including associated request savepoint data; instruction means responsive to receipt of a request instance on a selected subordinate process for updating a local savepoint with the request savepoint data associated and locally generated savepoint data; instruction means for executing the request instance for each selected subordinate process; instruction means for indicating to a coordination process success or failure of execution on each request instance; and instruction means responsive to indication of failure of execution for any request instance of the selected request for performing a rollback on each subordinate process which the local savepoint indicates executed a request instance for the selected request.

Claim 15

A data processing program product for assuring atomicity of distributed update requests on a parallel database management system wherein each distributed update request comprises a plurality of request instances which may span a plurality of subordinate processes, said data processing program product comprising media storing: instruction means for distributing a plurality of request instances for a selected request to a plurality of subordinate processes, each request instance including associated request savepoint data; instruction means responsive to receipt of a request instance on a selected subordinate process for updating a local savepoint with the request savepoint data associated and locally generated savepoint data; instruction means for executing the request instance for each selected subordinate process; instruction means for indicating to a coordination process success or failure of execution on each request instance; and instruction means responsive to indication of failure of execution for any request instance of the selected request for performing a rollback on each subordinate process which the local savepoint indicates executed a request instance for the selected request.

Claim 16

A data processing program product as set forth in claim 12, the media further comprising: instruction means responsive to initiation of a transaction for initializing a request counter for the coordination process; instruction means responsive to receipt of a request from an application program by the coordination process for incrementing the request counter for the coordination process; and the instruction means for distributing including instruction means for passing the request counter as request savepoint data.

Claim 17

A data processing program product as set forth in claim 13, wherein locally generated savepoint data includes a log sequence number tracking instances of changes to a partition.

Claim 18

A data processing program product as set forth in claim 14, the media further comprising: instruction means responsive to initiation of a transaction for initializing the local savepoint for all of a plurality of distributed processes by setting the local request counter and the log sequence number to value indicating no prior issuance of request savepoint data.

Claim 19

A data processing program product as set forth in claim 15, wherein the instruction means for updating of a local savepoint further includes instruction means for adding a current value for the log sequence number to the savepoint.

Claim 20

A data processing program product as set forth in claim 16, the media further comprising: instruction means responsive to issuance of a request instance to a selected subordinate process for discarding any prior savepoint for the selected subordinate processes; instruction means responsive to rolling back to a savepoint on a subordinate process for discarding the savepoint; and instruction means responsive to conclusion of the transaction for discarding savepoints across all subordinate processes.