Database replication with host replication at asynchronously replicated system

Patent metadata

Field	Value
Publication number	US-12332913-B2
Application number	US-202318228446-A
Country	US
Kind code	B2
Filing date	Jul 31, 2023
Priority date	Jul 31, 2023
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

Various examples are directed to systems and methods for operating a primary database management system and a secondary database management system. The secondary database management system may receive a takeover request indicating that the secondary database management system is to assume a role of the primary database system. The secondary database management system may determine that a last valid commit of a first host of the secondary database system is an oldest last valid commit. The secondary database management system may revert to a first state of the primary database management system corresponding to the last valid commit of the first host. The secondary database management system may be configured to assume the role of the primary database management system.

First claim

What is claimed is:

1. A system comprising:
a secondary database management system configured to asynchronously replicate a primary database management system remote from the secondary database management system, the secondary database management system comprising a first host performing a first source role, a second host performing a first replica role for the first source role, a third host performing a second source role, and a fourth host performing a second replica role for the second source role, the first host, the second host, third host, and fourth host being executable software components of the secondary database management system, the first host and the second host being for managing a first portion of data stored by the secondary database management system the third host and the fourth host being for managing a second portion of the data stored by the secondary database management system, and the secondary database management system being programmed to execute operations comprising:
receiving, by a coordinator component of the secondary database management system, a takeover request, the takeover request indicating that the secondary database management system is to assume a role of the primary database management system;
determining, by the coordinator component, that a last valid commit of the first host is an oldest last valid commit;
reverting the secondary database management system to a first state of the primary database management system corresponding to the last valid commit of the first host; and
after reverting the secondary database management system to the first state of the primary database management system, configuring the secondary database management system to assume the role of the primary database management system.

2. The system of claim 1 , the operations further comprising:
before receiving the takeover request, receiving, from the primary database management system, a first redo log describing a data change made by at least one host at the primary database management system;
determining, by the coordinator component, that the data change described by the first redo log corresponds to the first host; and
sending the first redo log to the first host.

3. The system of claim 2 , the operations further comprising:
replaying, by the first host, the first redo log;
determining, by the first host, that the second host has also replayed the first redo log; and
after determining that the second host has also replayed the first redo log, committing a transaction corresponding to the first redo log.

4. The system of claim 1 , the operations further comprising:
before receiving the takeover request receiving, from the primary database management system, a first redo log describing a first change made by at least one host at the primary database management system;
determining, by the coordinator component, that the first change described by the first redo log corresponds to the first host;
determining, by the coordinator component, that the first redo log is not a next redo log for the first host; and
caching, by the coordinator component, the first redo log.

5. The system of claim 4 , the operations further comprising:
receiving, from the primary database management system, a second redo log describing a second change made by at least one host at the primary database management system;
determining, by the coordinator component, that the second change described by the first redo log corresponds to the first host;
determining, by the coordinator component, that the second redo log is the next redo log for the first host; and
sending, by the coordinator component, redo log data to the first host, the redo log data comprising the first redo log and the second redo log.

6. The system of claim 5 , the operations further comprising:
replaying, by the first host, the second redo log; and
after replaying the second redo log, replaying, by the first host, the first redo log.

7. The system of claim 1 , a last valid commit for the third host corresponding to a second state of the primary database management system, the operations further comprising determining that the first state of the primary database management system is older than the second state of the primary database management system.

8. The system of claim 1 , the reverting of the secondary database management system to the first state of the primary database management system comprising using at least one redo log to reverse at least one commit at the third host.

9. A method for operating a primary database management system and a secondary database management system remote from the primary database management system, the secondary database management system comprising a first host performing a first source role, a second host performing a first replica role for the first source role, a third host performing a second source role, and a fourth host performing a second replica role for the second source role, the first host, the second host, third host, and fourth host being executable software components of the secondary database management system, the first host and the second host being for managing a first portion of data stored by the secondary database management system the third host and the fourth host being for managing a second portion of the data stored by the secondary database management system, the method comprising:
receiving, by a coordinator component of the secondary database management system, a takeover request, the takeover request indicating that the secondary database management system is to assume a role of the primary database management system;
determining, by the coordinator component, that a last valid commit of the first host is an oldest last valid commit;
reverting the secondary database management system to a first state of the primary database management system corresponding to the last valid commit of the first host; and
after reverting the secondary database management system to the first state of the primary database management system, configuring the secondary database management system to assume the role of the primary database management system.

10. The method of claim 9 , further comprising:
before receiving the takeover request, receiving, from the primary database management system, a first redo log describing a data change made by at least one host at the primary database management system;
determining, by the coordinator component, that the data change described by the first redo log corresponds to the first host; and
sending the first redo log to the first host.

11. The method of claim 10 , further comprising:
replaying, by the first host, the first redo log;
determining, by the first host, that the second host has also replayed the first redo log; and
after determining that the second host has also replayed the first redo log, committing a transaction corresponding to the first redo log.

12. The method of claim 9 , further comprising:
before receiving the takeover request receiving, from the primary database management system, a first redo log describing a first change made by at least one host at the primary database management system;
determining, by the coordinator component, that the first change described by the first redo log corresponds to the first host;
determining, by the coordinator component, that the first redo log is not a next redo log for the first host; and
caching, by the coordinator component, the first redo log.

13. The method of claim 12 , further comprising:
receiving, from the primary database management system, a second redo log describing a second change made by at le

Assignees

• Sap Se

Inventors

• Behrens Markus
• Singer Reiner
• Thesing Werner
• Zhu Yue
• Saleh Omran

Classifications

• G06F16/27

  Replication, distribution or synchronisation of data between databases or within a distributed database system; Distributed database system architectures therefor · CPC title

• G06F16/273 Primary

  Asynchronous replication or reconciliation · CPC title