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: 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: 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: 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: In an embodiment, a benzene sensor comprises a substrate having an iodine complex disposed thereon, a radiation source configured to project UV radiation onto the complex, and a UV detector configured to detect a UV reflection off of the substrate having the iodine complex. The iodine complex can include a cyclodextrine-iodine complex such as an alpha-cyclodextrine-iodine complex, a ?-cyclodextrine iodine complex, or any combination thereof.

Abstract: Apparatus and associated methods relate to a compact gas sensor (CGS) including a housing with a central stepped cavity with one or more first lead contact(s) forming a portion of a base plane in a bottom of the cavity and one or more second lead contact(s) forming a portion of a stepped plane higher than the base plane, the cavity sized to receive a chemically based stack of material made up of a bottom diffusion electrode layer, a middle electrolyte gel layer, and a top diffusion electrode layer. The bottom diffusion electrode layer is in electrical contact with the first lead contact(s). The top diffusion electrode layer electrically couples to the second lead contact(s) via an overlaying micro electromechanical system (MEMS) element layer with conductive coating. In an illustrative example, the CGS may provide gas sensing in small spaces.

Abstract: Storing an incoming data stream using successive files that are consecutively populated. The appropriate file to populate a given data stream portion into is determined by mapping the data stream offset to a file, and potentially also an address within that file. The successive files may be the same size, so that the file can be identified based on the data stream address (or offset) without the use of an index. Furthermore, the files may be easily named by having that size be some multiple of a binary power of bytes. That way, the files themselves can be automatically and named and identified by using the more significant bit or bits of the data stream offset to uniquely identify the file and establish ordering of the files. Replication may occur from a primary to a secondary store by transmitting the offset, and the actual data to be stored.

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: The creation of transaction segment records that are each associated with transaction segments within a log that includes multiple tasks, each of at least some associated with a corresponding transaction. The transaction segment records each include a transaction identifier set that define which tasks are included within the transaction segment. The transaction identifier sets are non-overlapping such that the transaction segments may be processed substantially in parallel by dispatching the transaction segment records to different worker threads. The identity of a latest external dependee entity, if any, is included within the transaction segment record. Upon being assigned a transaction segment for processing, the module assigned the transaction segment awaits completion of processing of the latest external dependee entity prior to processing the transaction segment.

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.

Abstract: A lockless open collection data structure used to create a sequence of collection records. The sequence of collection records may be inserted into a data stream for purposes of assisting in subsequent processing of the data stream in a parallel manner, by collection. The open collection data structure is re-usable for multiple collections of data items within the data stream. The use of the open collection data structure may occur while a data stream that includes multiple different types of data items is being evaluated. The open collection data structure is used to track an expandable collection definition of a currently open collection. Upon detecting that the collection definition is no longer expandable, the collection record is created based on state within the open collection data structure. Once the collection record for a collection has been created, the open collection data structure becomes available for the next collection record.

Abstract: A log manager causing events to be written to the primary and the secondary computing systems for high availability, and returning threads quickly. Rather than cause every event write to be immediately written to the secondary computing system, the log management component is triggered to write to the secondary computing system upon detecting event write requests of event writes of a particular event type. In response to detecting such an event write, the log management component gathers a group of event writes corresponding to that particular event write, and dispatches the event writes as a group. The particular thread that initiated the particular event write of the particular event type is returned after dispatching the event write group, but before or without confirmation of the particular event write group has been written to the secondary computing system.

Abstract: The use of a skip element when redoing transactions, so as to avoid tracking dependencies between transactions assigned to different threads for parallel processing. When the second thread comes to a second task in the course of redoing a second transaction, if a first task that is mooted by the second task is not already performed, the second thread inserts a skip element associated with the object to be operated upon by the particular task, instead of actually performing the particular task upon the object. When the first thread later comes to the first task in the course of redoing a first transaction, the first thread encounters the skip element associated with the object. Accordingly, instead of performing the dependee task, the first thread skips the dependee task and perhaps removes the skip element. The result is the same regardless of whether the first or second task is redone first.

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 is implemented as a lock-free data structure and 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: A versioned records management system that uses a restart era in order to promote rapid recovery. A persistent store includes a plurality of items that are each marked with a restart era. Any item that was created in the current restart era is marked with the current restart era. The persistent store also includes a first subset of the items comprising a plurality of records. At least one record includes multiple corresponding versions. The persistent store also includes a second subset of the items comprising a collection of objects that conform to an object model that is used to operate upon the plurality of records via the object collection. The versioned records management system recovers from a crash by promoting an item in the persistent store to the current restart era, in parallel with normal operation of the versioned records management system.

Abstract: The logging of tasks associated with multiple transactions in the context in which the computing system is capable of having multiple of the transactions active at a given time, and thus in which the order of completion of the transactions is not guaranteed to be the same as the order of initiation of the transactions. A sequence of transaction segment records is added to the log. Each transaction segment record comprises a transaction identifier range that does not overlap with the transaction identifier range in any of the sequence of transaction segment records including the transaction identifier range of any neighboring transaction segment record in the sequence of transaction segment records. Each transaction segment record also includes a log entry identifier range extending from the first task of the first of the transactions to be initiated to the last task of the last transaction to complete.

Abstract: A log manager causing events to be written to the primary and the secondary computing systems for high availability, and returning threads quickly. Rather than cause every event write to be immediately written to the secondary computing system, the log management component is triggered to write to the secondary computing system upon detecting event write requests of event writes of a particular event type. In response to detecting such an event write, the log management component gathers a group of event writes corresponding to that particular event write, and dispatches the event writes as a group. The particular thread that initiated the particular event write of the particular event type is returned after dispatching the event write group, but before or without confirmation of the particular event write group has been written to the secondary computing system.

Abstract: The use of a skip element when redoing transactions, so as to avoid tracking dependencies between transactions assigned to different threads for parallel processing. When the second thread comes to a second task in the course of redoing a second transaction, if a first task that is mooted by the second task is not already performed, the second thread inserts a skip element associated with the object to be operated upon by the particular task, instead of actually performing the particular task upon the object. When the first thread later comes to the first task in the course of redoing a first transaction, the first thread encounters the skip element associated with the object. Accordingly, instead of performing the dependee task, the first thread skips the dependee task and perhaps removes the skip element. The result is the same regardless of whether the first or second task is redone first.