Method, system, and program for merging log entries from multiple recovery log files
First Claim
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1. A method for merging log entries from multiple recovery logs, comprising:
- recording local transactions with log entries within each of the multiple recovery logs;
recording causally ordered, ascending timestamp information for selected ones of the log entries in each of the multiple recovery logs, wherein the timestamp information is used to order global transactions;
sequentially examining the log entries of each of the multiple recovery logs in an order based on the causally ordered, ascending timestamp information;
merging the log entries from each of the multiple recovery logs that form local transactions to form global transactions; and
outputting the merged log entries in the order of the causally ordered, ascending timestamp information.
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Abstract
Provided are a method, system, and program for merging independent log entries in a multiple node shared nothing DBMS. Initially, log entries from multiple log entries are combined to form a single log entry sequence. Local transactions are generated from the single log entry sequence and stored in a local transactions structure. In particular, log entries with the same local transaction identifier form a local transaction. Then, local transactions having the same global identifier are merged to form global transactions.
172 Citations
27 Claims
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1. A method for merging log entries from multiple recovery logs, comprising:
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recording local transactions with log entries within each of the multiple recovery logs; recording causally ordered, ascending timestamp information for selected ones of the log entries in each of the multiple recovery logs, wherein the timestamp information is used to order global transactions; sequentially examining the log entries of each of the multiple recovery logs in an order based on the causally ordered, ascending timestamp information; merging the log entries from each of the multiple recovery logs that form local transactions to form global transactions; and outputting the merged log entries in the order of the causally ordered, ascending timestamp information. - View Dependent Claims (2, 3, 4)
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5. A method for restarting merging of recovery log entries from multiple recovery logs, comprising:
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bolding restart information in persistent recoverable storage for a restart, wherein the restart resumes replication of changes while not missing any of the recovery log entries and while capturing each of the recovery log entries once for a given logged transaction, and wherein the restart information includes log sequence numbers; and merging and processing each logged transaction using the restart information. - View Dependent Claims (6, 7, 8, 9)
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10. A system for merging log entries from multiple recovery logs, comprising:
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a set of nodes, each node having a recovery log; and a computer program executable by a computer, wherein the computer program comprises instructions for; recording local transactions with log entries within each of the multiple recovery logs; recording causally ordered, ascending timestamp information for selected ones of the log entries in each of the multiple recovery logs, wherein the timestamp information is used to order global transactions; sequentially examining the log entries of each of the multiple recovery logs in an order based on the causally ordered, ascending timestamp information; merging the log entries from each of the multiple recovery logs that form local transactions to form global transactions; and outputting the merged log entries in the order of the causally ordered, ascending timestamp information. - View Dependent Claims (11, 12, 13)
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14. A system for restarting merging of recovery log entries from multiple recovery logs, comprising:
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a set of nodes, each node having a recovery log; and a computer program executable by a computer, wherein the computer program comprises instructions for; holding restart information in persistent recoverable storage for a restart, wherein the restart resumes replication of changes while not missing any of the recovery log entries and while capturing each of the recovery log entries once for a given logged transaction, and wherein the restart information includes log sequence numbers; and merging and processing each logged transaction using the restart information. - View Dependent Claims (15, 16, 17, 18)
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19. An article of manufacture including code for merging log entries from multiple recovery logs, wherein the code is capable of causing operations, the operations comprising:
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recording local transactions with log entries within each of the multiple recovery logs; recording causally ordered, ascending timestamp information for selected ones of the log entries in each of the multiple recovery logs, wherein the timestamp information is used to order global transactions; sequentially examining the log entries of each of the multiple recovery logs in an order based on the causally ordered, ascending timestamp information; merging the log entries from each of the multiple recovery logs that form local transactions to form global transactions; and outputting the merged log entries in the order of the causally ordered, ascending timestamp information. - View Dependent Claims (20, 21, 22)
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23. An article of manufacture including code for restarting the merging of recovery log entries from multiple recovery logs, wherein the code is capable of causing operations, the operations comprising:
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holding restart information in persistent recoverable storage for a restart, wherein the restart resumes replication of changes while not missing any of the recovery log entries and while capturing each of the recovery log entries once for a given logged transaction, and wherein the restart information includes log sequence numbers; and merging and processing each logged transaction using the restart information. - View Dependent Claims (24, 25, 26, 27)
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Specification