Abstract: Methods and apparatus are described for splitting a page (or node) in an index tree database index for a multi-master database. The methods include creating a first split page of a first page. The first page belongs to a first set of pages and comprises a hinge page. The hinge page also belongs to a second set of pages. Updating the first set of pages may cause the hinge page itself to split, creating a split of the hinge page. The second set of pages is updated in response to creating the split of the hinge page. Described are techniques whereby the updates to the first and second sets of pages are atomic, that is, they all succeed or they all fail, which may realize any of several benefits.

Abstract: The present disclosure provides methods, systems and apparatus for efficient data management in distributed database system. According to an aspect, a method is provided. The method includes relocating a first table and a second table of a database to a first node of the database, wherein the first table and a second table (or one or more tables which have a colocation relationship with the first table) are associated with one or more distribution keys corresponding to one or more columns of the first table and the second table. The method further includes defining a colocation relationship between the first table and the second table based on a distribution key of the one or more distribution keys. The colocation relationship may indicate that data of the first table and the second table that correspond according to the distribution key are to reside on a same node of the database.

Abstract: A method and system of processing database transactions in a distributed online transaction processing (OLTP) database is provided. Overhead and network bandwidth associated with a global transaction manager are reduced and scalability improved by determining whether incoming statements are single-shard or multi-shard. For single-shard statements, a local transaction identifier (TXID) stored and associated with a data record reference by the statement is retrieved. The retrieved TXID is compared against a copy of a list of prepared transactions that are pending in a respective data node. If the TXID is in the copy of the prepared list, the statement is caused to await until the previous transaction has been committed or aborted. The visibility of a change committed by the previous is then determined, and the statement is processed.

Abstract: A method and system of processing database transactions in a distributed online transaction processing (OLTP) database is provided. Overhead and network bandwidth associated with a global transaction manager are reduced and scalability improved by determining whether incoming statements are single-shard or multi-shard. For single-shard statements, a local transaction identifier (TXID) stored and associated with a data record reference by the statement is retrieved. The retrieved TXID is compared against a copy of a list of prepared transactions that are pending in a respective data node. If the TXID is in the copy of the prepared list, the statement is caused to await until the previous transaction has been committed or aborted. The visibility of a change committed by the previous is then determined, and the statement is processed.

Abstract: This application provides a data processing method and apparatus. The method includes: receiving, by a master storage node, information that is about a first transaction and that is sent by a read-write node, where the information about the first transaction is used to request to perform a write operation on first data stored on the master storage node; determining, by the master storage node, the first data based on the information about the first transaction, and executing the first transaction; generating, by the master storage node, first transaction status metadata when the first transaction ends, where the first transaction status metadata includes identification information of expired data and identification information of the first transaction; and sending, by the master storage node, the first transaction status metadata to at least one read-only node. According to the data processing method and apparatus, a read delay of a read-only node can be eliminated.

Abstract: Generating, by a first primary site that is included in a group of primary sites of a distributed database system, a commit action redo log message for a commit action performed by the first primary site for a first database transaction, the commit action redo log message including a transaction ID for the first database transaction and a transaction order indicator that represents an order of database transactions in a group of database transactions performed at one or more primary sites of the group of primary sites; and sending, by the first primary site, the commit action redo log message, for a corresponding first standby site that backs up the first primary site.

Abstract: The disclosed systems and methods are directed for detecting and resolving write-write conflicts among a plurality of transactions received from master nodes of a multi-writer database system. The method includes receiving a plurality of REDO logs and storing the plurality of REDO logs in a buffer, each REDO log associated with the one of the plurality of transactions, selecting one REDO log of the plurality of REDO logs; persisting the transaction associated with the one REDO log in a local storage when a write-write conflict is detected between the one REDO log and at least one other REDO log of the plurality of REDO logs prior to committing the transaction associated with the one REDO log; and transmitting a status of the transaction associated with the one REDO log to a global transaction manager (GTM).

Abstract: Generating, by a first primary site that is included in a group of primary sites of a distributed database system, a commit action redo log message for a commit action performed by the first primary site for a first database transaction, the commit action redo log message including a transaction ID for the first database transaction and a transaction order indicator that represents an order of database transactions in a group of database transactions performed at one or more primary sites of the group of primary sites; and sending, by the first primary site, the commit action redo log message, for a corresponding first standby site that backs up the first primary site.

Abstract: Generating, by a first primary site that is included in a group of primary sites of a distributed database system, a commit action redo log message for a commit action performed by the first primary site for a first database transaction, the commit action redo log message including a transaction ID for the first database transaction and a transaction order indicator that represents an order of database transactions in a group of database transactions performed at one or more primary sites of the group of primary sites; and sending, by the first primary site, the commit action redo log message, for a corresponding first standby site that backs up the first primary site.

Abstract: A method and system for implementing concurrency control in a database system includes receiving a request from a node for handling by a GTM. Registering the request in a slot in a tracking array where each of the slots represents one of the requests for handling by the GTM. A slot is acquired, and a segment of the tracking array is scanned to determine a batch of pending requests. The batch is used to produce an aggregate request and the aggregate request includes an aggregate increment of a total number of commit requests of the batch. The aggregate request is sent to the GTM using one of a plurality of pre-established connections. A response is received from the GTM that includes a current value of an incremented timestamp. The incremented timestamp is distributed to the requests of the batch and the lock is released.

Abstract: Methods and apparatus are described for splitting a page (or node) in an index tree database index for a multi-master database. The methods include creating a first split page of a first page. The first page belongs to a first set of pages and comprises a hinge page. The hinge page also belongs to a second set of pages. Updating the first set of pages may cause the hinge page itself to split, creating a split of the hinge page. The second set of pages is updated in response to creating the split of the hinge page. Described are techniques whereby the updates to the first and second sets of pages are atomic, that is, they all succeed or they all fail, which may realize any of several benefits.

Abstract: The disclosed systems, structures, and methods are directed towards for processing a lock request by a master node to access a shared data object in a database located at a remote location comprising identifying, in the master node, a category of the lock request. If the lock request is for a self-compatible lock, determining a value of a counter associated with the master node and with one or more other master nodes, and if the value of the counter is zero, locally granting the lock request. If the value of the counter is greater than zero, forwarding the lock request to a global lock manager (GLM), and if the lock request is for a heavy-conflicting lock, forwarding the lock request by the master node to the GLM.

Abstract: The disclosed computing node comprises a processor and a non-transitory storage medium storing instructions executable by the processor. A method and a system are also disclosed. A subset of a plurality of conventional redo records, corresponding to received write requests, is selected based on an identical data location identifier. The conventional redo records of such selected subset are combined into a consolidated redo record. The consolidated redo record is then transmitted to a target node for processing.

Abstract: The disclosed systems and methods are directed for detecting and resolving write-write conflicts among a plurality of transactions received from master nodes of a multi-writer database system. The method includes receiving a plurality of REDO logs and storing the plurality of REDO logs in a buffer, each REDO log associated with the one of the plurality of transactions, selecting one REDO log of the plurality of REDO logs; persisting the transaction associated with the one REDO log in a local storage when a write-write conflict is detected between the one REDO log and at least one other REDO log of the plurality of REDO logs prior to committing the transaction associated with the one REDO log; and transmitting a status of the transaction associated with the one REDO log to a global transaction manager (GTM).

Abstract: The disclosed systems, structures, and methods are directed towards for processing a lock request by a master node to access a shared data object in a database located at a remote location comprising identifying, in the master node, a category of the lock request. If the lock request is for a self-compatible lock, determining a value of a counter associated with the master node and with one or more other master nodes, and if the value of the counter is zero, locally granting the lock request. If the value of the counter is greater than zero, forwarding the lock request to a global lock manager (GLM), and if the lock request is for a heavy-conflicting lock, forwarding the lock request by the master node to the GLM.

Abstract: The disclosed computing node comprises a processor and a non-transitory storage medium storing instructions executable by the processor. A method and a system are also disclosed. A subset of a plurality of conventional redo records, corresponding to received write requests, is selected based on an identical data location identifier. The conventional redo records of such selected subset are combined into a consolidated redo record. The consolidated redo record is then transmitted to a target node for processing.

Abstract: This application provides a data processing method and apparatus. The method includes: receiving, by a master storage node, information that is about a first transaction and that is sent by a read-write node, where the information about the first transaction is used to request to perform a write operation on first data stored on the master storage node; determining, by the master storage node, the first data based on the information about the first transaction, and executing the first transaction; generating, by the master storage node, first transaction status metadata when the first transaction ends, where the first transaction status metadata includes identification information of expired data and identification information of the first transaction; and sending, by the master storage node, the first transaction status metadata to at least one read-only node. According to the data processing method and apparatus, a read delay of a read-only node can be eliminated.

Abstract: Provided are techniques for savepoint processing. One of a savepoint statement, a rollback to savepoint statement, and a release savepoint statement is received. It is determined whether to propagate the received one of the savepoint statement, the rollback to savepoint statement, and the release savepoint statement to a data source based on an asymmetrical model in which a nested level of savepoints on a federated server side is capable of being greater than a nested level of savepoints on a data source side and wherein a two-tiered data structure is used to preserve savepoint information in the asymmetrical model. In response to determining that propagation is to occur, the one of the savepoint statement, the rollback to savepoint statement, and the release savepoint statement is propagated to the data source.

Abstract: Disclosed is a data processing system-implemented method, a data processing system and an article for manufacture for directing a data processing system to roll back to a savepoint located in a unit of work having a boundary generated by a boundary generator. The data processing system-implemented method includes examining a savepoint status indicator associated with the savepoint, and rolling back past the boundary to the savepoint depending on whether the examined savepoint status indicator indicates rolling back past the boundary towards the savepoint is permitted.

Abstract: A method for releasing a nested savepoint on a remote node of a database management system. The to-be-released savepoint is one of a series of savepoints represented by control blocks arranged in a linked list in the creation order of the savepoints they represent. Releasing of the to-be-released savepoint begins with receiving of a request to release the to-be-released savepoint. A control block is selected such that it represents the to-be-released savepoint or the next more recently created savepoint after the to-be-released savepoint. The selected control block is merged with all other control blocks that represent savepoints that are more recently created than the savepoint represented by the selected control block. The resulting merged control block represents all of the savepoints from the most recently created to the savepoint previously represented by the selected control block.