Abstract: The subject disclosure relates to a distributed transaction management technique that ensures synchronization between participating nodes in a global or distributed database transaction. The technique leverages a commit protocol that uses local clocks at the respective participating nodes. Participants in a global transaction are configured to utilize the same commit timestamp and logical read time and can advance their respective local clocks to establish this synchronization. In one embodiment, distributed commit utilizes a modified version of two-phase commit that includes an extra phase to collect commit timestamp votes from participants. Additionally, a heartbeat mechanism can be used to establish loose synchronization between nodes. In another embodiment, a node can respond to a remote transaction request by returning a list of nodes involved in generating the result of the transaction and the types of access used by such nodes in addition to the transaction result itself.

Abstract: A transaction creates a wait for dependency on a version in a main memory database implementing a multi-version concurrency control scheme. The wait for dependency allows the transaction to update the version while other transactions are reading the version. The multi-version concurrency control scheme also allows commit dependencies to be implementing concurrently with wait for dependencies. Commit dependencies allow a transaction to read an updated version before the updated version is committed.

Abstract: A system and method for accelerating searches of B-trees. An auxiliary index that is optimized for use with a cache is used in conjunction with a B-tree. A hash type of auxiliary index maintains pointers to key entries in the B-tree leaf nodes. The hash type of index may be searched, and a resulting pointer is used to locate records of the B-tree, bypassing a search of the B-tree. A top level type of auxiliary index maintains pointers to leaf nodes or internal nodes of the B-tree. A top level index may be searched, and a search of the B-tree is performed beginning with the node found by using the top level index. A monitoring mechanism may automatically start, change, or discard the auxiliary index based on an amount of cache memory, types of searches, or other factors. The auxiliary index may be optimized for high performance in read only searches, while the B-tree provides transaction durability.

Abstract: The subject disclosure relates to a database recovery technique that implements various aspects of transaction logging to optimize database recovery performance. Transactions are logged logically with no reference to physical location, which enables logging to be performed via multiple independent log streams in parallel. A set of log streams can further be adjusted to conform to a local configuration of a mirror or secondary node in order to increase mirroring flexibility. Additionally, individual transactions or groups of transactions are recorded using a single log record, which contains timestamp information to enable database recovery without reference to physical checkpoint files. Further, techniques are provided herein for processing transactions without Write Ahead Logging or hardening of undo information.

Abstract: The subject disclosure relates to a distributed transaction management technique that ensures synchronization between participating nodes in a global or distributed database transaction. The technique leverages a commit protocol that uses local clocks at the respective participating nodes. Participants in a global transaction are configured to utilize the same commit timestamp and logical read time and can advance their respective local clocks to establish this synchronization. In one embodiment, distributed commit utilizes a modified version of two-phase commit that includes an extra phase to collect commit timestamp votes from participants. Additionally, a heartbeat mechanism can be used to establish loose synchronization between nodes. In another embodiment, a node can respond to a remote transaction request by returning a list of nodes involved in generating the result of the transaction and the types of access used by such nodes in addition to the transaction result itself.

Abstract: An operating system is provided. The system includes an agent component to monitor computer activities between one or more single-item access components (SIAC) and one or more set-based access components (SBAC). An interface component is employed by the agent component to process kernel mode requests from a user mode application when communicating with a storage platform. Re-try components can be provided to facilitate cooperation between the SIAC and the SBAC.

Abstract: The present invention extends to methods, systems, and computer program products for mirroring file data. Generally, high availability and disaster recovery (“HADRON”) is achieved within a database management system by detecting which parts of a file have changed and sending the changed parts to secondaries. Adjacent or partially overlapping parts of a file can coalesce to form larger chunks of changed data. Coalescing reduces the overall number of chunks that are tracked.

Abstract: A method for mirroring one or more data changes from a first database server to one or more second database servers. The method includes intercepting one or more operations that make one or more changes to one or more data on the first database server. After intercepting these operations, the method merges the operations into one or more chunks, adds one or more log records having the chunks into a database log. The database log includes one or more database log blocks. The method then writes the database log blocks.

Abstract: A database management system having a database component, which includes a lock manager, and a filesystem component. The filesystem component is configured to: generate a mapping between one or more filesystem access modes, one or more filesystem sharing modes and one or more database locks, receive a request from a filesystem stack to perform one or more actions on data in a database, identify a filesystem access mode and a filesystem share mode of the request, determine which one of the database locks corresponds to the filesystem access mode and the filesystem share mode of the request based on the mapping, and receive a notification lock on the data from the lock manager when no other database locks conflict with the notification lock, wherein the notification lock corresponds to the one of the database locks.

Abstract: A computer system includes a memory and a processor coupled to the memory. The processor is configured to execute instructions that cause execution of an in-memory database system that includes one or more database tables. Each database table includes a plurality of rows, where data representing each row is stored in the memory. The in-memory database system also includes a plurality of indexes associated with the one or more database tables, where each index is implemented by a lock-free data structure. Update logic at the in-memory database system is configured to update a first version of a particular row to create a second version of the particular row. The in-memory database system includes a non-blocking garbage collector configured to identify data representing outdated versions of rows.

Abstract: The subject disclosure relates to a concurrency control technique that ensures isolation among concurrently execution transactions optimistically in a multiversion database by applying two optional tests at the end of a read-write transaction: validating the visibility of the read set of the read-write transaction(s) and phantom detection by re-scanning and confirming no new version have appeared in the view. Depending on desired level of isolation, both, one or none of the test are applied. Each version of a data record in an applicable database can be assigned two timestamps indicating the lifetime the version. The value of a version timestamp, though assigned, may be conditional on a transaction committing.

Abstract: The claimed subject matter provides a system and/or a method that extends transactional guarantees to unstructured data in a file system. A database engine, configured to retain structured data, can reserve a portion of the file system to store unstructured data to be managed by the database engine. A kernel component can associate a transaction with at least one stream that corresponds to the reserved portion of the file system. The association enables transaction based access to the reserved portion of the file system managed by the database engine.

Abstract: A system and method for accelerating searches of B-trees. An auxiliary index that is optimized for use with a cache is used in conjunction with a B-tree. A hash type of auxiliary index maintains pointers to key entries in the B-tree leaf nodes. The hash type of index may be searched, and a resulting pointer is used to locate records of the B-tree, bypassing a search of the B-tree. A top level type of auxiliary index maintains pointers to leaf nodes or internal nodes of the B-tree. A top level index may be searched, and a search of the B-tree is performed beginning with the node found by using the top level index. A monitoring mechanism may automatically start, change, or discard the auxiliary index based on an amount of cache memory, types of searches, or other factors. The auxiliary index may be optimized for high performance in read only searches, while the B-tree provides transaction durability.

Abstract: The claimed subject matter provides a system and/or a method that extends transactional guarantees to unstructured data in a file system. A database engine, configured to retain structured data, can reserve a portion of the file system to store unstructured data to be managed by the database engine. A kernel component can associate a transaction with at least one stream that corresponds to the reserved portion of the file system. The association enables transaction based access to the reserved portion of the file system managed by the database engine.

Abstract: An operating system is provided. The system includes an agent components (SIAC) and one or more set-based access components (SBAC). An interface component is employed by the agent component to process kernel mode requests from a user mode application when communicating with a storage platform. Re-try components can be provided to facilitate cooperation between the SIAC and the SBAC.

Abstract: A piston for a striker is displaceable in a cylinder and forms compartments on opposite sides which can selectively be connected by hydraulically controlled valve elements to a pump and to an accumulator. A hydraulic controller for the valve elements initially connects a compartment on one side of the piston to contribute the pressure from a respective compartment to the accumulator during a lifting operation, cuts off the valve element affording this pressure accumulation to brake the piston, and other such valve elements enable the accumulator to be charged with the piston in its raised position so that, upon triggering by the controller of the valve elements, the pressure which drives the ram is equal to the total pressure delivered by the accumulator and the pump to the piston.