Abstract: In one aspect, a computerized method for managing tombstones in a node of a Distributed Database Base System (DDBS) includes the step of providing a rule that, for a namespace in a record of the node of the DDBS that allows expiration, mandates that a later generation's expiration time of the namespace never decreases. The computerized method includes the step of determining that an administrator of the DDBS has set an expiration time of the namespace to infinity. The computerized method includes the step of implementing a background process of the DDBS, wherein the background process scans a DDBS node's drive and flags a set of extant tombstones that are no longer covering viable namespaces or viable records. The computerized method includes the step of deleting all the flagged tombstones.

Abstract: In one aspect, a computerized method useful for operating a database management system DMBS DBMS in a strong consistency mode comprising includes the step of implementing an atomic transfer of a master node of the DMBS DBMS. The method includes the step of implementing a master node restriction, wherein the master node restriction guarantees no more than one master node is ever available. The information about a set of nodes participating in a cluster of the set node of the DMBS DBMS is maintained to allow a subset of nodes to determine that the one master node is a master of a subset of data stored in the cluster.

Abstract: In one aspect, a computerized method for managing consistency and availability tradeoffs in a real-time operational database management system (DBMS) includes the step of implementing consistency in an AP mode of the real-time operational DBMS by implementing the following steps. The method adds a set of schemes that enable a real-time operational DBMS to linearize read/write operations in all situations except a first specified situation and a second specified situation. The real-time operational DBMS is in AP mode, at least one master node for every data item is available in the database cluster of the real-time operational DBMS at all times. The method implements a CP mode of operation.

Abstract: A computer-implemented method of a distributed database system includes generating a database index. The method includes mapping a first specified number of bits of the database index to a database key. The method includes mapping a second specified number of bits to a data object associated with the database key. The method includes storing the first specified number of bits of the database key in a dram memory. The method includes storing second specified number of bits with the data object in a solid-state device (SSD) storage.

Abstract: In one aspect, a computerized-method of a distributed database includes the step of providing a first data partition with a set of data. The method includes the step of providing a second data partition with a replica of the first set of data. The method includes the step of identifying a client application accessing the first data partition and the second data partition. The method includes the step of performing a reclamation operation on the second data partition. The method includes the step of informing the client application that a read operation is prohibited during the reclamation operation.

Abstract: in one aspect, a computerized method for managing consistency and availability tradeoffs in a real-time operational database management system (DBMS) includes the step of implementing consistency in an AP mode of the real-time operational DBMS by implementing the following steps. The method adds a set of schemes that enable a real-time operational DBMS to linearize read/write operations in all situations except a first specified situation and a second specified situation. The real-time operational DBMS is in AP mode, at least one master node for every data item is available in the database cluster of the real-time operational DBMS at all times. The method implements a CP mode of operation.

Abstract: In one aspect, a computerized method useful for operating a database management system DMBS in a strong consistency mode comprising includes the step of implementing an atomic transfer of a master node of the DMBS. The method includes the step of implementing a master node restriction, wherein the master node restriction guarantees no more than one master node is ever available. The information about a set of nodes participating in a cluster of the set node of the DMBS is maintained to allow a subset of nodes to determine that the one master node is a master of a subset of data stored in the cluster. The method includes the step of implementing a hybrid clock in the DBMS. The method includes the step of implementing a replication integrity policy. The replication integrity policy guarantees a strict consistency between the set of nodes and maintains replication integrity using a redo mechanism to ensure that no read operations or write operations are allowed when replicas are in an unknown state.

Abstract: A method of a data distribution across nodes of a Distributed Database Base System (DDBS) includes the step of hashing a primary key of a record into a digest, wherein the digest is part of a digest space of the DDBS. The method includes the step of partitioning the digest space of the DDBS into a set of non-overlapping partitions. The method includes the step of implementing a partition assignment algorithm. The partition assignment algorithm includes the step of generating a replication list for the set of non-overlapping partitions. The replication list includes a permutation of a cluster succession list. A first node in the replication list comprises a master node for that partition. A second node in the replication list comprises a first replica. The partition assignment algorithm includes the step using the replication list to generate a partition map.

Abstract: In one aspect, a computerized method for managing tombstones in a node of a Distributed Database Base System (DDBS) includes the step of providing a rule that, for a namespace in a record of the node of the DDBS that allows expiration, mandates that a later generation's expiration time of the namespace never decreases. The computerized method includes the step of determining that an administrator of the DDBS has set an expiration time of the namespace to infinity. The computerized method includes the step of implementing a background process of the DDBS, wherein the background process scans a DDBS node's drive and flags a set of extant tombstones that are no longer covering viable namespaces or viable records. The computerized method includes the step of deleting all the flagged tombstones.

Abstract: In one aspect, a computerized-method of a distributed database includes the step of providing a first data partition with a set of data. The method includes the step of providing a second data partition with a replica of the first set of data. The method includes the step of identifying a client application accessing the first data partition and the second data partition. The method includes the step of performing a reclamation operation on the second data partition. The method includes the step of informing the client application that a read operation is prohibited during the reclamation operation.

Abstract: A computer-implemented method of a distributed database system includes generating a database index. The method includes mapping a first specified number of bits of the database index to a database key. The method includes mapping a second specified number of bits to a data object associated with the database key. The method includes storing the first specified number of bits of the database key in a dram memory. The method includes storing second specified number of bits with the data object in a solid-state device (SSD) storage.

Abstract: In one exemplary aspect, a method of a distributed database system includes the step of detecting that a database node departed from a database cluster. A consensus-based voting process is implemented utilizing all of a set of other database nodes remaining in the database cluster. A cluster configuration is determined with the consensus-based voting process. The cluster configuration includes a new list of the set of other database nodes remaining in the database cluster. The data is automatically rebalanced among the set of other database nodes remaining in the database cluster according to the cluster configuration. Optionally, the consensus-based voting process can include a Paxos algorithm. The database cluster can be a Not-Only SQL (NOSQL) distributed database cluster.

Abstract: In one exemplary aspect, a method of a cluster-node load balancing system of a distributed database system includes receiving a request from a cluster with at least one node of a cluster of the distributed database system. The request includes a query for an identity of all other nodes known by the node as well as a metadata of all data maintained by the node. The identity of all other nodes known by the node as well as the metadata of all data maintained by the node is provided to the cluster.

Abstract: In one exemplary aspect, a method of a distributed database system includes the step of detecting that a database node departed from a database cluster. A consensus-based voting process is implemented utilizing all of a set of other database nodes remaining in the database cluster. A cluster configuration is determined with the consensus-based voting process. The cluster configuration includes a new list of the set of other database nodes remaining, in the database cluster. The data is automatically rebalanced among the set of other database nodes remaining in the database cluster according to the cluster configuration. Optionally, the consensus-based voting process can include a Paxos algorithm. The database cluster can be a Not-Only SQL (NOSQL) distributed database cluster.

Abstract: In one exemplary aspect, a method of a cluster-node load balancing system of a distributed database system includes receiving a request from a cluster with at least one node of a cluster of the distributed database system. The request includes a query for an identity of all other nodes known by the node as well as a metadata of all data maintained by the node. The identity of all other nodes known by the node as well as the metadata of all data maintained by the node is provided to the cluster.

Abstract: In one exemplary aspect, a method a Peripheral Component Interconnect Express (PCIe) based switch that provides a bridge between a set of database nodes of the distributed database system is provided. A failure in a database node is detected. A consensus algorithm is implemented to determine a replacement database node. A database index of a data storage device formally managed by the database node that failed is migrated to a replacement database node. The PCIe-based switch is remapped to attach the replacement database node with the database index to the data storage device.

Abstract: In one exemplary embodiment, a method of a distributed database system includes the step receiving a query in a query language from a client with a distributed database system. An index that matches the query is located. The index is pre-generated from a database table in the distributed database system. A map function of a MapReduce programming model is implemented using the index. A reduce function of the MapReduce programming model is implemented using the output of the map function. Optionally, a finalize function can be implemented using the output of the reduce function. The distributed database system can be a scalable NoSQL database. The reduce function can be optional when the value of the output of the map function is guaranteed to be unique.

Abstract: In one exemplary embodiment, a method of a distributed database system includes the step receiving a query in a query language from a client with a distributed database system. An index that matches the query is located. The index is pre-generated from a database table in the distributed database system. A map function of a MapReduce programming model is implemented using the index. A reduce function of the MapReduce programming model is implemented using the output of the map function. Optionally, a finalize function can be implemented using the output of the reduce function. The distributed database system can be a scalable NoSQL database. The reduce function can be optional when the value of the output of the map function is guaranteed to be unique.

Abstract: In one exemplary embodiment, a method of a distributed database system includes the step of receiving a database transaction with a node of the distributed database system. A priority of the database transaction is determined. A load of a transaction queue of the node is determined. The execution of a database transaction is delayed if the load of the transaction queue is greater than a first-water mark. The database transaction is delayed for a specified period. A portion of the database transaction is execution after the specified period. It is determined if the load of the queue is below a second-water mark after the specified period. A remaining portion of the database transaction can be processed if the load of the queue is below the second-water mark.

Abstract: In one exemplary embodiment, a method of a distributed database system includes the step receiving a query in a query language from a client with a distributed database system. An index that matches the query is located. The index is pre-generated from a database table in the distributed database system. A map function of a MapReduce programming model is implemented using the index. A reduce function of the MapReduce programming model is implemented using the output of the map function. Optionally, a finalize function can be implemented using the output of the reduce function. The distributed database system can be a scalable NoSQL database. The reduce function can be optional when the value of the output of the map function is guaranteed to be unique.