Abstract: Methods and systems are described for managing a shared database. One or more processing nodes may access a shared database. A common log node may manage the shared database. The common log node may validate database operations requested by the one or more processing nodes. During validation, the common log node may detect conflicts that occur between database operations requested by the one or more processing nodes.

Abstract: A computer implemented method includes receiving multiple requests to update a data structure stored in non-volatile memory (NVM) and applying an atomic multiword update to the data structure to arbitrate access to the NVM. In a further embodiment, a computer implemented method includes allocating a descriptor for a persistent multi-word compare-and-swap operation (PMwCAS), specifying targeted addresses of words to be modified, returning an error if one of the targeted addresses contains a value not equal to a corresponding compare value, executing the operation atomically if the targeted addresses contain values that match the corresponding compare values, and aborting the operation responsive to the returned error.

Abstract: Methods, systems, and computer-readable media of columnar storage of a database index are disclosed. A particular columnar index includes a column store that stores rows of the columnar index in a column-wise fashion and a delta store that stores rows of the columnar index in a row-wise fashion. The column store also includes an absence flag array. The absence flag array includes entries that indicate whether certain rows have been logically deleted from the column store.

Abstract: Systems and methods for switching a data access synchronization strategy for a data structure are provided. Workload characteristics of one or more threads of execution access the data structure are monitored. A target data access synchronization strategy is determined. If the current strategy is different than the target strategy, the current strategy is switched to the target data access synchronization strategy for the data structure.

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: Various technologies described herein pertain to accessing records of an in-memory database. A memory can include a primary storage and a data store can include a secondary storage. The primary storage includes a first subset of the records of the database, and the secondary storage includes a second subset of the records of the database. Moreover, the memory includes an update memo that includes timestamp notices. The timestamp notices specify statuses of records of the database having updates that span the primary storage and the secondary storage. The memory further includes a database management system that is executable by a processor. The database management system processes a transaction. Further, the database management system includes a storage interface component that accesses a record of the database for the transaction based on at least one of the timestamp notices of the update memo.

Abstract: A system that uses a persistent main memory to preserve events that await logging in a persistent store. Each event is written into the persistent main memory so as to be loggable in case of recovery. For instance, the event may be written into a log cache structure, along with other state which identifies that the event is in the particular log cache structure, the location of the event within the particular log cache structure, and the order of the event. To recover, the log in the persistent store is evaluated to identify the end of the stored log. The tail of the log is identified in the persistent main memory by identifying any log cache structures that are after the end of the stored log and which are validly recoverable. The log cache structure contents are then serialized one log cache at a time, earliest first.

Abstract: A versioned records management computing system that uses a restart era in order to promote rapid recovery. A persistent store includes a multi-versioned record collection. The records are also associated with a restart era that corresponds to the era of operation of the computing system after a restart. Upon a recovery, the current restart era changes. An object collection media has an object collection that conforms to an object model such that the object model is used to operate upon the records. The object collection media is operable such that the object collection is durable so as to survive restarts of the system to thereby allow for accelerated recovery.

Abstract: A computer implemented method includes receiving multiple requests to update a data structure stored in non-volatile memory (NVM) and applying an atomic multiword update to the data structure to arbitrate access to the NVM. In a further embodiment, a computer implemented method includes allocating a descriptor for a persistent multi-word compare-and-swap operation (PMwCAS), specifying targeted addresses of words to be modified, returning an error if one of the targeted addresses contains a value not equal to a corresponding compare value, executing the operation atomically if the targeted addresses contain values that match the corresponding compare values, and aborting the operation responsive to the returned error.

Abstract: An apparatus is disclosed. The apparatus may be implemented in a database node or a storage node and includes one or more processors and memory storing instructions for causing the processor to perform a number of operations. Responsive to a page write request, the apparatus determines an identifier corresponding to the requested page, sends component blocks corresponding to the page to a storage node for appending to an append-only storage log of the storage node, receives the physical location of the stored component blocks, and associates the physical storage location of the stored component blocks with the logical identifier corresponding to the page.

Abstract: An in-memory database system stores an entirety of a database within main memory of the computer system. The database includes a table comprising a plurality of rows including a particular row. A first transaction updating the particular row is executed to create a first version of the particular row. A second transaction updating the particular row is executed to create a second version of the particular row. The first version is visible only to the first transaction, and the second version is visible only to the second transaction. The in-memory database system may associate an index with the database table, the index referencing the plurality of rows, including referencing the first version of the particular row and the second version of the particular row. The in-memory database system may initiate garbage collection of the first version of the particular row and/or the second version of the particular row.

Abstract: Various technologies described herein pertain to accessing records of an in-memory database. A memory can include a primary storage and a data store can include a secondary storage. The primary storage includes a first subset of the records of the database, and the secondary storage includes a second subset of the records of the database. Moreover, the memory includes an update memo that includes timestamp notices. The timestamp notices specify statuses of records of the database having updates that span the primary storage and the secondary storage. The memory further includes a database management system that is executable by a processor. The database management system processes a transaction. Further, the database management system includes a storage interface component that accesses a record of the database for the transaction based on at least one of the timestamp notices of the update memo.

Abstract: A versioned records management computing system that uses a restart era in order to promote rapid recovery. A persistent store includes a multi-versioned record collection. The records are also associated with a restart era that corresponds to the era of operation of the computing system after a restart. Upon a recovery, the current restart era changes. An object collection media has an object collection that conforms to an object model such that the object model is used to operate upon the records. The object collection media is operable such that the object collection is durable so as to survive restarts of the system to thereby allow for accelerated recovery.

Abstract: An in-memory database system stores the entirety of a database that is being operated on by a database system within main memory. The database includes a table that comprises a plurality of rows including a particular row. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index references the plurality of rows, including referencing the first and second versions of the particular row. A transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the transaction based on the first valid time and the second version of the particular row being not visible to the transaction based on the second valid time.

Abstract: Performing a transaction in the context of a computing system that has one or more persistent systems coupled to one or more processors over a bus. As an example, the persistent system may serve as at least part of the main memory of the computing system. The transaction might implement multi-versioning in which a record is not updated in place. Rather, each record is represented as a sequence of one or more record versions, each version having a valid interval during which the record version is considered to properly represent the record. The transaction processing uses torn write detection so that recovery processes may use such guards to verify that there are no torn writes. For instance, torn write guards may be used to verify the integrity of record versions as well as the log buffers that refer to the record versions.

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 in-memory database system stores the entirety of a database that is being operated on by a database system within main memory. The database includes a table that comprises a plurality of rows including a particular row. The database table comprises a first version of the particular row having a first valid time, and a second version having a second valid time. Index(es) are associated with the database table. Each index references the plurality of rows, including referencing the first and second versions of the particular row. A transaction acting on the first version of the particular row is executed. The first version of the particular row is visible to the transaction based on the first valid time and the second version of the particular row being not visible to the transaction based on the second valid time.

Abstract: The efficient use of threads that issue calls to log events. While waiting for the call to return or complete, the threads are put to work on other tasks that are not part of the process that generated the event. This can occur without context switching of the thread, especially when the task to be performed is state-less or context free. In the efficient thread diversion process, the thread calls a logging component to log an event. This blocks the thread from continuing work on a process that the event is part of until the event is logged. The thread then performs a diversion task that is not part of the processing unit that the event is part of. After detecting that the event has logged, the thread continues work on the processing unit that the event is part of.

Abstract: A system and method to process a dataset with a database management system (DBMS) engine. The method includes splitting bulk data into a plurality of chunks. The method also includes converting the chunks to a plurality of row groups. The row groups are a dataset external to a DBMS comprising the DBMS engine. The method further includes creating an empty DBMS table within the DBMS. Additionally, the method includes attaching the dataset external to the DBMS to the empty DBMS table. The method also includes executing a MapReduce job on a cluster of compute nodes, using the dataset external to the DBMS as input.

Abstract: The subject disclosure relates to a distributed transaction management technique that ensures synchronization between participating nodes in a global or distributed 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.