Abstract: In response to a read request directed to a first data store of a storage group, a state transition indicator is identified, corresponding to a modification that has been applied at the data store before a response to the read is prepared. A read descriptor that includes the state transition indicator and read repeatability verification metadata is prepared. The metadata can be used to check whether the read request is a repeatable read. The read descriptor is transmitted to a client-side component of the storage group.

Abstract: At a client-side component of a storage group, a read descriptor generated in response to a read request directed to a first data store is received. The read descriptor includes a state transition indicator corresponding to a write that has been applied at the first data store. A write descriptor indicative of a write that depends on a result of the read request is generated at the client-side component. The read descriptor and the write descriptor are included in a commit request for a candidate transaction at the client-side component, and transmitted to a transaction manager.

Abstract: A journaled database system may comprise data nodes that maintain a collection of data structured in accordance with a schema. A change to the schema may be applied by a journal module while a journal consumer continues to operate using a prior version of the schema. A buffer may be formed and have stored therein records describing state change instructions according to the prior view of the schema. An index of correspondence between the records in the buffer and in the source journal may be maintained.

Abstract: A forking coordinator of a journal-based multi-data-store database determines that a forking criterion for a first journal has been met. The coordinator stores an indication that processing of transaction requests directed to a particular subset of the database is suspended. The coordinator instantiates a second journal for storing committed transaction entries for the particular subset. Metadata of the second journal indicates that transaction entries with sequence numbers in a particular range are stored in the first journal. The coordinator stores an indication that transaction processing associated with the particular subset of the system is to be resumed using the second journal.

Abstract: A test coordinator for an application whose data is to be stored at a journal-based multi-data-store database using an optimistic concurrency control protocol identifies a test descriptor. The test descriptor indicates a particular order of a plurality of events associated with the application's data, such as reads from various data stores and propagations of committed writes from the database journal to the data stores. The test coordinator uses a set of control mechanisms to cause the events to occur in a selected execution environment in the particular order, and stores an indication of a state reached by the application in response to the events.

Abstract: A journaled database system may comprise data nodes that maintain a collection of data structured in accordance with a schema. A change to the schema may be applied by a journal module while a journal consumer continues to operate using a prior version of the schema. A buffer may be formed and have stored therein records describing state change instructions according to the prior view of the schema. An index of correspondence between the records in the buffer and in the source journal may be maintained.

Abstract: A journal manager of a multi-data-store storage appends a committed transaction entry to a journal, indicating a state change which has been approved for commit using an optimistic concurrency control algorithm. A first representation of the state change is generated and stored at one materialization node. A different representation of the same state change, comprising at least one attribute for which a value is not included in the first representation, is generated and stored at a different materialization node.

Abstract: A materialization configuration request is received via a programmatic interface from a client of a journal-based multi-data-store database. The request indicates a partitioning rule to be used to select, for respective writes indicated in committed transaction entries of a journal, the materialization node at which the writes are to be stored. A control plane component of the database verifies that a set of materialization nodes corresponding to the partitioning rule has been established, and initiates the propagation of writes from the journal to the materialization nodes by respective write appliers.

Abstract: A data store manager of a multi-data-store journal-based database performs a sequential analysis of committed transaction entries of a journal. A particular entry includes a directive to determine a value of an attribute of a data object based on a result obtained from a value generator, and does not specify the value of the attribute. The data store manager determines the value using a local version of the value generator, and stores the value in a materialized version of the data object. In response to a programmatic read request, the data store manager provides the materialized version of the data object.

Abstract: A transaction request is received at a journal-based state management system. The transaction request includes a register processing section indicating an operation to be performed at a journal register allocated to the transaction submitter to store state information of an application. Based on the results of a conflict detection operation performed with respect to the transaction request and on the result of the operation on the journal register, the transaction request is accepted for commit. The value of the journal register is stored at a node of the state management system and provided to the transaction submitter.

Abstract: A materialization configuration request is received via a programmatic interface from a client of a journal-based multi-data-store database. The request indicates a partitioning rule to be used to select, for respective writes indicated in committed transaction entries of a journal, the materialization node at which the writes are to be stored. A control plane component of the database verifies that a set of materialization nodes corresponding to the partitioning rule has been established, and initiates the propagation of writes from the journal to the materialization nodes by respective write appliers.

Abstract: A system may comprise a storage device on which counters are stored. A counter may be associated with an identifier. A computing node of the system may receive a request to modify the counter. In response to the request, a read signature may be stored and may comprise a hash of the identifier and a tolerance of the counter to change. A write signature may be stored in response to the request, and may comprise a hash of the identifier and a magnitude of the requested modification. A conflict may be detected by comparing a sum of the magnitudes of requested changes to the tolerance of the read operation.

Abstract: A journal manager of a multi-data-store storage system receives a transaction which includes a message to be stored in the storage system's journal if the transaction request is accepted for commit. The journal manager performs a conflict detection operation, accepts the transaction request, and stores a corresponding committed transaction entry including the message in the journal. A write applier associated with a registered materialization node of the journal reads the committed transaction entry and applies a write indicated in the entry. A registered message subscriber of the journal reads the committed transaction entry asynchronously with respect to the write applier, and reads the contents of the message without applying the write.

Abstract: A transaction request is received at a journal-based state management system. The transaction request includes a register processing section indicating an operation to be performed at a journal register allocated to the transaction submitter to store state information of an application. Based on the results of a conflict detection operation performed with respect to the transaction request and on the result of the operation on the journal register, the transaction request is accepted for commit. The value of the journal register is stored at a node of the state management system and provided to the transaction submitter.

Abstract: Computing devices may synchronize respective copies of a repository in part by sharing status information for records stored in the repository. Status information may be conveyed by encoding record identifiers in a hashtable. A hash function may be selected to have an output range equal to or larger than a number of records in the repository. A plurality of hash function outputs may be mapped to a storage location containing a sum of identifiers and a count of identifiers included in the sum. The storage location may be transmitted to a remote computing device, which may unfold the data in the storage location to identify changed records.

Abstract: At a client-side component of a storage group, a read descriptor generated in response to a read request directed to a first data store is received. The read descriptor includes a state transition indicator corresponding to a write that has been applied at the first data store. A write descriptor indicative of a write that depends on a result of the read request is generated at the client-side component. The read descriptor and the write descriptor are included in a commit request for a candidate transaction at the client-side component, and transmitted to a transaction manager.

Abstract: A device may participate in a shared data state in which editing operations performed locally are distributed and synchronized with other devices participating in the shared data state. Data may be maintained in log-structured storage files on each device. Changes made locally may be represented by change descriptors conditionally appended to the end of a log. The size of the log may be monotonically increasing. Monotonically increasing identifiers may be used to implicitly or explicitly identify change descriptors. Upon conflict resolution, conditionally appended change descriptors may be committed. Non-committed change descriptors may be conditionally reappended to the end of the log for further conflict resolution.

Abstract: At a client-side component of a storage group, a read descriptor generated in response to a read request directed to a first data store is received. The read descriptor includes a state transition indicator corresponding to a write that has been applied at the first data store. A write descriptor indicative of a write that depends on a result of the read request is generated at the client-side component. The read descriptor and the write descriptor are included in a commit request for a candidate transaction at the client-side component, and transmitted to a transaction manager.

Abstract: A first transaction manager of a partitioned storage group stores a first conditional commit record for a first write of a multi-partition transaction based on a first conflict detection operation. A second transaction manager stores a second conditional commit record for a second write of the transaction based on a second conflict detection operation. A client-side component of the storage group determines that both writes have been conditionally committed, and stores an unconditional commit record in a commit decision repository. A write applier examines the first conditional commit record and the unconditional commit record before propagating the first write to the first partition.

Abstract: A first transaction manager of a partitioned storage group stores a first conditional commit record for a first write of a multi-partition transaction based on a first conflict detection operation. A second transaction manager stores a second conditional commit record for a second write of the transaction based on a second conflict detection operation. A client-side component of the storage group determines that both writes have been conditionally committed, and stores an unconditional commit record in a commit decision repository. A write applier examines the first conditional commit record and the unconditional commit record before propagating the first write to the first partition.