Abstract: A method is provided for resharding a sharded database sharded according to a first shard key. The method includes: receiving, by a processor an instruction to reshard the sharded database; receiving, at the processor, a new shard key to be used in a resharding process to reshard the sharded database; determining, by the processor, whether a duration of unavailability of the sharded database during the resharding process is less than a predetermined amount of time; and automatically performing, by the processor, the resharding process according to the new shard key to produce a resharded database, if the duration of unavailability is less than the predetermined amount of time. The method may be performed without users noticing a significant interruption to read/write operations from/to the database.

Abstract: In some embodiments, a database cluster to cluster synchronization system may include multiple replicators coupled to a source database cluster and a destination database cluster, where the source and destination cluster may be shard clusters. Each of the multiple replicators may correspond to a respective subset of the source database cluster and configured to monitor changes of data on the respective subset of the source database cluster and translate the changes of data to one or more database operations to be performed on the destination cluster. The changes of data on the source database may be contained in respective change streams associated with each of the replicators.

Abstract: In some embodiments, a database cluster to cluster synchronization system may include multiple replicators coupled to a source database cluster and a destination database cluster, where the source and destination cluster may be shard clusters. Each of the multiple replicators may correspond to a respective subset of the source database cluster and configured to monitor changes of data on the respective subset of the source database cluster and translate the changes of data to one or more database operations to be performed on the destination cluster. The changes of data on the source database may be contained in respective change streams associated with each of the replicators.

Abstract: Described herein are embodiments of a database system for performing multi-document transactions. The database system comprises a database comprising a plurality of data storage nodes. The database system receives transactions that access at least two documents stored in the database. The database system generates a transaction identifier associated with the transaction and associates operations in the transaction with the transaction identifier. The database system performs at least part of the transaction on the database and determines whether an error occurred in performing in performing the transaction. When the database system determines that an error occurred in performing the transaction, the database system reverses any performed operations of the transaction. When no error occurs in performing the transaction, the database system outputs a confirmation.

Abstract: According to aspects of the disclosure, there is provided a scalable cloud distributed database system for hosting data of multiple database tenants. In some embodiments, the database may be serverless. The serverless database may be configured to automatically and dynamically match resources to workload demands for tenants of the database. Databases described herein may include replica sets hosting multiple tenants. Tenants may be migrated from one replica set to another replica set based on usage. Usage of tenants may be throttled during migration between replica sets. Tenants with lower usage may be selected for migration between replica sets. During migration, files containing both a document and a history of updates to the document may be migrated. Databases described herein may include multiple storage tiers having different read and/or write speeds.

Abstract: A method is provided for resharding a sharded database sharded according to a first shard key. The method includes: receiving, by a processor an instruction to reshard the sharded database; receiving, at the processor, a new shard key to be used in a resharding process to reshard the sharded database; determining, by the processor, whether a duration of unavailability of the sharded database during the resharding process is less than a predetermined amount of time; and automatically performing, by the processor, the resharding process according to the new shard key to produce a resharded database, if the duration of unavailability is less than the predetermined amount of time. The method may be performed without users noticing a significant interruption to read/write operations from/to the database.

Abstract: According to some aspects, a database system is provided. The database system may include at least one processor configured to execute a plurality of system components. The plurality of system components may include an interface component configured to receive a read commit command and provide a result, a snapshot component configured to generate a plurality of snapshots of data stored in a first data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to read the committed snapshot responsive to receipt of the read commit command and generate the result.

Abstract: Described herein are embodiments of a database system for performing multi-document transactions. The database system comprises a database comprising a plurality of data storage nodes. The database system receives transactions that access at least two documents stored in the database. The database system generates a transaction identifier associated with the transaction and associates operations in the transaction with the transaction identifier. The database system performs at least part of the transaction on the database and determines whether an error occurred in performing in performing the transaction. When the database system determines that an error occurred in performing the transaction, the database system reverses any performed operations of the transaction. When no error occurs in performing the transaction, the database system outputs a confirmation.

Abstract: According to some aspects, a database system comprising a processor configured to execute a plurality of system components is provided. The plurality of system components may include an interface component configured to receive a write commit command and provide a write commit confirmation, a snapshot component configured to generate a plurality of snapshots of data stored in a data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to modify a data element based on the write commit command, determine whether the majority of the plurality of storage nodes have replicated the modification using the committed snapshot, and generate the write commit confirmation responsive to a determination that the majority of the plurality of data storage nodes have replicated the modification.

Abstract: Described herein are embodiments of a database system for performing multi-document transactions. The database system comprises a database comprising a plurality of data storage nodes. The database system receives transactions that access at least two documents stored in the database. The database system generates a transaction identifier associated with the transaction and associates operations in the transaction with the transaction identifier. The database system performs at least part of the transaction on the database and determines whether an error occurred in performing in performing the transaction. When the database system determines that an error occurred in performing the transaction, the database system reverses any performed operations of the transaction. When no error occurs in performing the transaction, the database system outputs a confirmation.

Abstract: A system and method for determining consensus within a distributed database are provided. According to one aspect, a protocol is provided that reduces or eliminates heartbeat communication between nodes of a replica set. Nodes may communicate liveness information using existing database commands and metadata associated with the database commands. According to another aspect, improved systems and methods are provided for detection of node failures and election of a new primary node.

Abstract: Systems and methods are provided for managing read requests in a database system. The same read request is communicated to multiple nodes to reduce long tail latency. If the read request is communicated to two nodes and the first node is experiencing a communication failure, the read request is serviced by the second node. Once a response is received from the second node, the read request to the first node can be canceled.

Abstract: According to some aspects, a database system is provided. The database system may include at least one processor configured to execute a plurality of system components. The plurality of system components may include an interface component configured to receive a read commit command and provide a result, a snapshot component configured to generate a plurality of snapshots of data stored in a first data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to read the committed snapshot responsive to receipt of the read commit command and generate the result.

Abstract: According to some aspects, a database system comprising a processor configured to execute a plurality of system components is provided. The plurality of system components may include an interface component configured to receive a write commit command and provide a write commit confirmation, a snapshot component configured to generate a plurality of snapshots of data stored in a data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to modify a data element based on the write commit command, determine whether the majority of the plurality of storage nodes have replicated the modification using the committed snapshot, and generate the write commit confirmation responsive to a determination that the majority of the plurality of data storage nodes have replicated the modification.

Abstract: According to some aspects, a database system is provided. The database system may include at least one processor configured to execute a plurality of system components. The plurality of system components may include an interface component configured to receive a read commit command and provide a result, a snapshot component configured to generate a plurality of snapshots of data stored in a first data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to read the committed snapshot responsive to receipt of the read commit command and generate the result.

Abstract: According to some aspects, a database system comprising a processor configured to execute a plurality of system components is provided. The plurality of system components may include an interface component configured to receive a write commit command and provide a write commit confirmation, a snapshot component configured to generate a plurality of snapshots of data stored in a data storage node of a plurality of data storage nodes and identify a committed snapshot representative of data that has been replicated on a majority of the plurality of data storage nodes, and a command processing component configured to modify a data element based on the write commit command, determine whether the majority of the plurality of storage nodes have replicated the modification using the committed snapshot, and generate the write commit confirmation responsive to a determination that the majority of the plurality of data storage nodes have replicated the modification.

Abstract: A system and method for determining consensus within a distributed database are provided. According to one aspect, a protocol is provided that reduces or eliminates heartbeat communication between nodes of a replica set. Nodes may communicate liveness information using existing database commands and metadata associated with the database commands. According to another aspect, improved systems and methods are provided for detection of node failures and election of a new primary node.

Abstract: A system and method for determining consensus within a distributed database are provided. According to one aspect, a protocol is provided that reduces or eliminates heartbeat communication between nodes of a replica set. Nodes may communicate liveness information using existing database commands and metadata associated with the database commands. According to another aspect, improved systems and methods are provided for detection of node failures and election of a new primary node.

Abstract: Described herein are embodiments of a database system for performing multi-document transactions. The database system comprises a database comprising a plurality of data storage nodes. The database system receives transactions that access at least two documents stored in the database. The database system generates a transaction identifier associated with the transaction and associates operations in the transaction with the transaction identifier. The database system performs at least part of the transaction on the database and determines whether an error occurred in performing in performing the transaction. When the database system determines that an error occurred in performing the transaction, the database system reverses any performed operations of the transaction. When no error occurs in performing the transaction, the database system outputs a confirmation.

Abstract: According to one aspect, a distributed database system is configured to manage write operations received from database clients and execute the write operations at primary nodes. The system then replicates received operations across a plurality of secondary nodes. Write operation can include safe write requests such that the database guaranties the operation against data loss once acknowledged. In some embodiments, the system incorporates an enhanced arbiter role the enables the arbiter to participate in cluster-wide commitment of data. In other embodiments, the enhanced arbiter role enables secondary nodes to evaluate arbiter operations logs when determining election criteria for new primary nodes.