Abstract: A dynamic proxy may be implemented for a database that can establish a connection between the proxy and a database engine to perform a database queries received from a client at the proxy. The proxy may receive a connection request (and later database queries) through a first network endpoint from a client. The proxy can then determine based on the source of the connection request a second network endpoint through which to access the database (e.g., the endpoint of the database engine). Once the proxy establishes a connection with the database engine through the second network endpoint, the proxy can request the performance of queries at the database engine instead of the client.

Abstract: A database system may include a database service and a separate distributed storage service. The database service (or a database engine head node thereof) may be responsible for query parsing, optimization, and execution, transactionality, and consistency, while the storage service may be responsible for generating data pages from redo log records and for durability of those data pages. For example, in response to a write request directed to a particular data page, the database engine head node may generate a redo log record and send it, but not the data page, to a storage service node. The storage service node may store the redo log record and return a write acknowledgement to the database service prior to applying the redo log record. The server node may apply the redo log record and other redo log records to a previously stored version of the data page to create a current version.

Abstract: A corpus of information describing queries used to access a transactional data store may be used to identify analytical relationships that are not explicitly defined in a schema or supplied by a user. Join relationships may be identified based on field coincidence in elements of queries in the corpus. Join relationships may be indicative of dimensions and attributes of a dimension. Hierarchy levels for a dimension may be identified based on factors including data type, reference in an aggregating clause, and reference in a grouping clause.

Abstract: A multi-framework blockchain service may be implemented with a common interface to manage different types of blockchain networks. Requests to create a blockchain network may be received via an interface for the control plane that triggers the creation of the blockchain network according to an identified workflow. Various operations to change the blockchain network, including membership changes, node additions, governance changes, analytics changes, and monitoring changes may be allowed or denied by the control plane according to a distributed governance policy in effect for the blockchain network.

Abstract: History for data objects may be maintained to detect data events. An indication of an Extract, Transform, Load (ETL) process applied to one or more source data objects to generate one or more transformed data objects may be received. History for the source data objects may be updated to include the transformed data objects and the ETL process that generated the transformed data objects. An evaluation of the update may be performed to determine whether an event associated with the data lineage is triggered. If the event is triggered, a notification of the event may be sent to one or more subscribers for the event.

Abstract: Tiered storage may be implemented for processing data. Data processors may maintain some of a data set, including user data and metadata describing the user data, locally. The data set is also maintained a data store remote to the data processor. When processing requests are received, a determination is made as to whether the local portions of the data set can execute the processing request or one or more additional portions of the data set are needed from the remote data store. If additional portions of the data set are needed, then a request may be sent to the data store for the additional portions. Once received, the data processor may execute the processing request utilizing the additional portions. Portions of the data set maintained locally at the data processor may be selected and flushed from local storage to the remote data store.

Abstract: Recognizing unknown data objects may be implemented for data objects stored in a data store. Data objects that are identified as unknown may be accessed to retrieve a portion of the data object. Different representations of the data object may be generated for recognizing different data schemas. An analysis of the representations may be performed to identify a data schema for the unknown data object. The data schema may be stored in a metadata store for the unknown data object.

Abstract: Hybrid quorum policies may be implemented for access requests to state maintained in a distributed system. An update to state maintained in a distributed system may be sent to multiple nodes in the distributed system maintain the state in order to satisfy a hybrid quorum policy for updating the state in the distributed system. The hybrid quorum policy may include individual quorum policies for multiple quorum sets including nodes of the distributed system. Acknowledgments received from nodes in the distributed system indicating that the update is performed may be evaluated according to the individual quorum policies to determine whether the hybrid quorum policy is satisfied. If the hybrid quorum policy is satisfied, then the update to the state may be considered durable.

Abstract: A query optimizer may receive a query block that includes a hint. The hint may include a unique object identifier to specify an object to which the hint applies. In some instances, the object may correspond to a nested query block. A query optimization plan may be determined based, at least in part, on the hint. The query execution plan may then be executed to query a data store.

Abstract: Burst performance of a database query may be determined according to a size of the database query. A query to a database may be received. A size may be determined for the query. If the size is less than a size threshold assigned to a first query engine, then the query may be performed at the first query engine. If the size is greater than or equal to the size threshold assigned to the first query engine, then the query may be performed at a second query engine.

Abstract: History for data objects may be maintained to detect data events. An indication of an Extract, Transform, Load (ETL) process applied to one or more source data objects to generate one or more transformed data objects may be received. History for the source data objects may be updated to include the transformed data objects and the ETL process that generated the transformed data objects. An evaluation of the update may be performed to determine whether an event associated with the data lineage is triggered. If the event is triggered, a notification of the event may be sent to one or more subscribers for the event.

Abstract: A log-structured data store may implement optimized log storage for asynchronous log updates. In some embodiments, log records may be received indicating updates to data stored for a storage client and indicating positions in a log record sequence. The log records themselves may not be guaranteed to be received according to the log record sequence. Received log records may be stored in a hot log portion of a block-based storage device according to an order in which they are received. Log records in the hot log portion may then be identified to be moved to a cold log portion of the block-based storage device in order to complete a next portion of the log record sequence. Log records may be modified, such as compressed, or coalesced, before being stored together in a data block of the cold log portion according to the log record sequence.

Abstract: Data processing engines implement tiered data processing for distributed data in local and remote data stores. Requests to access distributed data including a data object in a remote data store are received at a data processing engine. A query plan is generated to service the access request. Different operations in the query plan are identified and assigned to one or more remote query processing engines that may access the remote data object. Requests to perform the different operations are sent to the one or more remote query processing engines. A final result is generated for the request based on the results received for the different operations from the remote query processing engine and results from operations performed with respect to locally stored data.

Abstract: A multi-column index is generated based on an interleaving of data bits for selectivity for efficient processing of data in a relational database system. Two or more columns may be identified for inclusion in the multi-column index for a relational database table. Based, at least in part, on the interleaving of data bits for selectivity from the identified columns, a multi-column index is generated for the relational database table that provides a respective index value for each entry in the relational database table. The entries of the relational database table may then be stored according to the index values of the multi-column index.

Abstract: A centralized data store may provide multiple processing environments access to data. Different data processing clients may determine structural data for a data set stored in a remote data store. An access coordination scheme may be implemented to grant permission to the different processing clients to perform various operations with respect to the portions of the data set. The data processing clients may then access the data set according to the structural data so that operations may be performed with respect to the data permitted by the access coordination scheme to the data processing clients.

Abstract: A database system may implement efficient database journaling using non-volatile system memory. An update to a database may be received, and log records indicating the update may be generated. A non-volatile portion of the system memory may be directly accessed to store the generated log records such that in the event of a failure of the database, the log records may be still maintained. Log records stored to the non-volatile portion of the system memory may be identified as durably persisted, in some embodiments. Log records may be identified and sent to block-based storage, in some embodiments. Recovery from a database system failure, in some embodiments, by obtaining log records from the non-volatile portion of system memory.

Abstract: A first column of a first database table may be transferred to a second table in a combined truncate and append operation in a transaction that may be atomic and reversible. References data for the first column may be removed from the first table and added to the second table. The combined operation may be reversed by removing, from the second table, references to blocks of data added to the second table prior to commencing the combined operation. A second column corresponding on a row-by-row basis to the first column may be added to the second table, where the data is indicative of visibility of data in the first column to other transactions on the second table.

Abstract: A network-based services provider may reserve and provision primary resource instance capacity for a given service (e.g., enough compute instances, storage instances, or other virtual resource instances to implement the service) in one or more availability zones, and may designate contingency resource instance capacity for the service in another availability zone (without provisioning or reserving the contingency instances for the exclusive use of the service). For example, the service provider may provision resource instance(s) for a database engine head node in one availability zone and designate resource instance capacity for another database engine head node in another availability zone without instantiating the other database engine head node. While the service operates as expected using the primary resource instance capacity, the contingency resource capacity may be leased to other entities on a spot market. Leases for contingency instance capacity may be revoked when needed for the given service (e.g.

Abstract: A multi-column index is generated based on an interleaving of data bits for selectivity for efficient processing of data in a relational database system. Two or more columns may be identified for inclusion in the multi-column index for a relational database table. Based, at least in part, on the interleaving of data bits for selectivity from the identified columns, a multi-column index is generated for the relational database table that provides a respective index value for each entry in the relational database table. The entries of the relational database table may then be stored according to the index values of the multi-column index.

Abstract: A database system may implement efficient database journaling using non-volatile system memory. An update to a database may be received, and log records indicating the update may be generated. A non-volatile portion of the system memory may be directly accessed to store the generated log records such that in the event of a failure of the database, the log records may be still maintained. Log records stored to the non-volatile portion of the system memory may be identified as durably persisted, in some embodiments. Log records may be identified and sent to block-based storage, in some embodiments. Recovery from a database system failure, in some embodiments, by obtaining log records from the non-volatile portion of system memory.