Abstract: Various examples are directed to systems and methods for operating a database management system. A first host of a first version may be executed at a first container of a cloud environment. A second host of a second version may be executed at a second container of the cloud environment. The first host may be configured to perform a source role and the second host may be configured to perform a replica role corresponding to the source role. A network layer executing at the cloud environment may receive a request directed to the second host. The network layer may determine that the request is consistent with allowed request data describing allowed requests and may send the request to the second host.

Abstract: A scale-out computing cluster may include a large number of computing servers and storage devices. In order to provide high reliability, the computing cluster must be able to handle failures of individual devices. Reliability of the computing cluster may be improved by providing a standby server for each active server in the computing cluster. If any active server fails, the corresponding standby server is activated. The failed server may be brought back online or replaced, at which time the restored server becomes the standby server for the now-active original standby server. During the restoration period, if any other active server fails, the standby server for that active server is immediately activated. As a result, the recovery ability of the computing cluster is only challenged if both servers of an active/standby pair fail during the restoration period, substantially improving reliability.

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.

Abstract: A scale-out computing cluster may include a large number of computing servers and storage devices. In order to provide high reliability, the computing cluster must be able to handle failures of individual devices. Reliability of the computing cluster may be improved by providing a standby server for each active server in the computing cluster. If any active server fails, the corresponding standby server is activated. The failed server may be brought back online or replaced, at which time the restored server becomes the standby server for the now-active original standby server. During the restoration period, if any other active server fails, the standby server for that active server is immediately activated. As a result, the recovery ability of the computing cluster is only challenged if both servers of an active/standby pair fail during the restoration period, substantially improving reliability.

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.

Abstract: Various examples described herein are directed to systems and methods for operating a database management system. A first host may be executed at a first container of a cloud environment. The first host may be configured according to a first set of operating parameters and may perform a source role. A second host may be executed at a second container of the cloud environment. The second host may be configured according to the first set of operating parameters and may perform a replica role or the source role. A request to modify at least one operating parameter of the first source may be received. A third host may be started at a third container and configured to perform at least one of the source role or the replica role for the source role. At least one of the first host or the second host may be shut down.

Abstract: Various examples are directed to systems and methods for operating a database management system. A first host of a first version may be executed at a first container of a cloud environment. A second host of a second version may be executed at a second container of the cloud environment. The first host may be configured to perform a source role and the second host may be configured to perform a replica role corresponding to the source role. A network layer executing at the cloud environment may receive a request directed to the second host. The network layer may determine that the request is consistent with allowed request data describing allowed requests and may send the request to the second host.

Abstract: A scale-out computing cluster may include a large number of computing servers and storage devices. In order to provide high reliability, the computing cluster must be able to handle failures of individual devices. Reliability of the computing cluster may be improved by providing a standby server for each active server in the computing cluster. If any active server fails, the corresponding standby server is activated. The failed server may be brought back online or replaced, at which time the restored server becomes the standby server for the now-active original standby server. During the restoration period, if any other active server fails, the standby server for that active server is immediately activated. As a result, the recovery ability of the computing cluster is only challenged if both servers of an active/standby pair fail during the restoration period, substantially improving reliability.

Abstract: Disclosed herein are system, method, and computer program product embodiments for coordinated replication of heterogeneous database stores. An embodiment operates by determining a synchronization point based on a commit log of a primary data center. A current log position of each of a plurality of secondary slave servers associated with a secondary master server of a secondary data center is requested. It is determined that the current log position of at least one of the secondary slave servers does not correspond to the logged position of a corresponding primary slave server relative to the synchronization point. An update indicating that the current log position of each of the secondary slave servers corresponds to the logged position of each of the relative corresponding primary slave servers is received. A replay of each of the secondary slave servers up to the synchronization point is initiated.

Abstract: Replicating a tenant database includes receiving at a source system a first request from a target system for replicating a first tenant database of the source system, which includes one or more first servers. Characteristics of the one or more first servers are sent to the target system to generate at the target system a second tenant database including one or more second servers. Each second server corresponds to one first server and has the same characteristics as the corresponding first server. Information from each first server is replicated, in an asynchronous mode, to the corresponding second server through a communication channel that is established between each first server and the second server. Upon receiving a second request for stopping the replication, a synchronous mode of processing statements from client applications of the first tenant database is entered. Related apparatus, systems, techniques and articles are described.

Abstract: Disclosed herein are system, method, and computer program product embodiments for coordinated replication of heterogeneous database stores. An embodiment operates by determining a synchronization point based on a commit log of a primary data center. A current log position of each of a plurality of secondary slave servers associated with a secondary master server of a secondary data center is requested. It is determined that the current log position of at least one of the secondary slave servers does not correspond to the logged position of a corresponding primary slave server relative to the synchronization point. An update indicating that the current log position of each of the secondary slave servers corresponds to the logged position of each of the relative corresponding primary slave servers is received. A replay of each of the secondary slave servers up to the synchronization point is initiated.

Abstract: Replicating a tenant database includes receiving at a source system a first request from a target system for replicating a first tenant database of the source system, which includes one or more first servers. Characteristics of the one or more first servers are sent to the target system to generate at the target system a second tenant database including one or more second servers. Each second server corresponds to one first server and has the same characteristics as the corresponding first server. Information from each first server is replicated, in an asynchronous mode, to the corresponding second server through a communication channel that is established between each first server and the second server. Upon receiving a second request for stopping the replication, a synchronous mode of processing statements from client applications of the first tenant database is entered. Related apparatus, systems, techniques and articles are described.

Abstract: A system for fixing a wire to a surface of an external fixator having a wire adapted to extend through bony structure fastened with respect to the surface. A bolt having a shaft which comprises a threaded section, a head section and at least one clamping element is provided wherein the bolt is adapted to extend through an opening in the external fixation element with a nut, and clamps the wire to the surface. A counter torque tool is used to provide a counter torque while fastening the wire with the bolt and the nut. The bolt comprises a counter torque opening and wherein the counter torque tool comprises a section which is adapted to engage into the counter torque opening of the bolt to apply the counter torque.