Abstract: Aspects of the current subject matter are directed to an approach in which a parallel load operation of file ID mapping containers is accomplished at start and/or restart of a database system. Parallel load operation of file ID mapping and/or large binary object (LOB) file ID mapping is done among a plurality of scanning engines into a plurality of data buffers that are associated with each of the plurality of scanning engines. Each scanning engine operates on a certain path of a page chain of a page structure including the mapping, causing the page chain to be split among scanning engines to process maps. Contents of the data buffers are pushed to mapping engines via a queue. The mapping engines load the file ID mapping and the LOB file ID mapping into maps for in-system access.

Abstract: Recovery of a database system by taking the database system offline is initiated. Thereafter, recovery operations specified by a redo log of the database system are replayed. A cleanup log is generated that identifies cleanup operations occurring during the replay of the recovery operations for garbage collection. Concurrent with the startup of the database, garbage collection of the cleanup operations as specified in the database savepoint is initiated. In addition, concurrent with the replay of the recovery operations, garbage collection of the cleanup operations specified by the cleanup log is initiated. The database system is later brought online after all of the recovery operations are replayed.

Abstract: A computer implemented method is provided for determining a delay between a first database and an associated replicated database by replicating transactions of the first database in the replicated database, determining a delay between the two databases based on a commit timestamp from the first database and a timestamp associated with the commit transaction becoming visible in the replicated database. Then, after a predefined period of time has elapsed since replicating the commit transaction, determining a second delay based on a timestamp associated with a heartbeat log and a replicated database system time. And, selectively determining to execute or deny a statement received by the replicated database based on the second delay. Related apparatus, systems, techniques and articles are also described.

Abstract: A method, a system, and a computer program product for executing a takeover process. A takeover process of a primary computing system by a secondary computing system is triggered. The secondary computing system stores transaction data replicated from the primary computing system. Writing of a redo log of transaction data of one or more transactions into storage by the primary computing system is suspended. The redo log is written by the primary computing system prior to the suspending is transmitted to the secondary computing system. The takeover process of the primary computing system by the secondary computing system is executed upon receiving and persisting the redo log at the secondary computing system.

Abstract: A computer implemented method is provided comprising receiving a group of transaction logs from a first database, allocating transaction logs from the group of transaction logs to a first queue and to a second queue, generating an end-of-group transaction log indicative of an end of the group of transaction logs, allocating the end-of-group log to the first queue and the second queue; replaying transaction logs from the first queue including the end-of-group transaction log allocated to the first queue, replaying transaction logs from the second queue including the end-of-group transaction log allocated to the second queue; and changing visibility of one or more transactions in response to replaying the end-of-group transaction log allocated to the first queue and the end-of-group transaction log allocated to the second queue. Related apparatus, systems, techniques and articles are also described.

Abstract: Aspects of the current subject matter are directed to an approach in which a parallel load operation of file ID mapping containers is accomplished at start and/or restart of a database system. Parallel load operation of file ID mapping and/or large binary object (LOB) file ID mapping is done among a plurality of scanning engines into a plurality of data buffers that are associated with each of the plurality of scanning engines. Each scanning engine operates on a certain path of a page chain of a page structure including the mapping, causing the page chain to be split among scanning engines to process maps. Contents of the data buffers are pushed to mapping engines via a queue. The mapping engines load the file ID mapping and the LOB file ID mapping into maps for in-system access.

Abstract: A method, a system, and a computer program product for executing a takeover process. A takeover process of a primary computing system by a secondary computing system is triggered. The secondary computing system stores transaction data replicated from the primary computing system. Writing of a redo log of transaction data of one or more transactions into storage by the primary computing system is suspended. The redo log is written by the primary computing system prior to the suspending is transmitted to the secondary computing system. The takeover process of the primary computing system by the secondary computing system is executed upon receiving and persisting the redo log at the secondary computing system.

Abstract: Receiving a statement including requests for database operations in a secondary database system storing data replicated from a primary database system by replaying transaction output generated by the primary database system; responsive to receiving the statement, requesting an allocation of memory from the secondary database system to support the requested database operations; generating an aggregated statement memory consumption value based on the amount of memory consumed by all statements executing in the secondary database system that are not associated with replaying the transaction logs; determining that the requested allocation of memory in addition to the aggregated statement memory consumption value exceeds a total statement execution memory limit indicating a total amount of memory that may be allocated to all database operations associated with statement execution in a secondary database system, and denying the requested allocation of memory.

Abstract: Recovery of a database system by taking the database system offline is initiated. Thereafter, recovery operations specified by a redo log of the database system are replayed. A cleanup log is generated that identifies cleanup operations occurring during the replay of the recovery operations for garbage collection. Concurrent with the startup of the database, garbage collection of the cleanup operations as specified in the database savepoint is initiated. In addition, concurrent with the replay of the recovery operations, garbage collection of the cleanup operations specified by the cleanup log is initiated. The database system is later brought online after all of the recovery operations are replayed.

Abstract: A system includes a non-volatile random access memory storing a column store main fragment of a column of a database table, and a processing unit to read the column store main fragment from the non-volatile random access memory. A volatile random access memory storing a column store delta fragment of the column of the database table may also be included, in which the processing unit is to write to the column store delta fragment. According to some systems, the stored column store main fragment is byte-addressable, and is copied from the volatile random access memory to the non-volatile random access memory without using a filesystem cache.

Abstract: Recovery of a database system by taking the database system offline is initiated. Thereafter, recovery operations specified by a redo log of the database system are replayed. A cleanup log is generated that identifies cleanup operations occurring during the replay of the recovery operations for garbage collection. Concurrent with the startup of the database, garbage collection of the cleanup operations as specified in the database savepoint is initiated. In addition, concurrent with the replay of the recovery operations, garbage collection of the cleanup operations specified by the cleanup log is initiated. The database system is later brought online after all of the recovery operations are replayed.

Abstract: A computer implemented method for replication includes registering a first database system with a second database system and performing a failback operation on the first database system. The failback operation includes opening a snapshot that includes data known to have existed on the first database system and the second database system at a first time. Transaction log information is requested from the second database system. The transaction log information corresponds to transactions performed on the second database system beginning with the first time. The transaction log information is applied to the snapshot data on the first database system. Related apparatus, systems, techniques and articles are also described.

Abstract: A computer implemented method is provided for determining a delay between a first database and an associated replicated database by replicating transactions of the first database in the replicated database, determining a delay between the two databases based on a commit timestamp from the first database and a timestamp associated with the commit transaction becoming visible in the replicated database. Then, after a predefined period of time has elapsed since replicating the commit transaction, determining a second delay based on a timestamp associated with a heartbeat log and a replicated database system time. And, selectively determining to execute or deny a statement received by the replicated database based on the second delay. Related apparatus, systems, techniques and articles are also described.

Abstract: A savepoint is initiated in an in-memory database system that is associated with a plurality of modified pages and comprises a pre-critical phase, a critical phase, and a post-critical phase. Thereafter, as part of the critical phase, a physical page number is assigned to each page in the critical phase. Further, as part of the critical phase, each page assigned a physical page number is individually locked. Subsequently, each page is handed over from a corresponding first thread to a corresponding second thread to copy such page into a corresponding shadow page as part of the post-critical phase.

Abstract: A computer implemented method is provided for determining a delay between a first database and an associated replicated database by replicating transactions of the first database in the replicated database, determining a delay between the two databases based on a commit timestamp from the first database and a timestamp associated with the commit transaction becoming visible in the replicated database. Then, after a predefined period of time has elapsed since replicating the commit transaction, determining a second delay based on a timestamp associated with a heartbeat log and a replicated database system time. And, selectively determining to execute or deny a statement received by the replicated database based on the second delay. Related apparatus, systems, techniques and articles are also described.

Abstract: A computer implemented method is provided comprising receiving a group of transaction logs from a first database, allocating transaction logs from the group of transaction logs to a first queue and to a second queue, generating an end-of-group transaction log indicative of an end of the group of transaction logs, allocating the end-of-group log to the first queue and the second queue; replaying transaction logs from the first queue including the end-of-group transaction log allocated to the first queue, replaying transaction logs from the second queue including the end-of-group transaction log allocated to the second queue; and changing visibility of one or more transactions in response to replaying the end-of-group transaction log allocated to the first queue and the end-of-group transaction log allocated to the second queue. Related apparatus, systems, techniques and articles are also described.

Abstract: Receiving a statement including requests for database operations in a secondary database system storing data replicated from a primary database system by replaying transaction output generated by the primary database system; responsive to receiving the statement, requesting an allocation of memory from the secondary database system to support the requested database operations; generating an aggregated statement memory consumption value based on the amount of memory consumed by all statements executing in the secondary database system that are not associated with replaying the transaction logs; determining that the requested allocation of memory in addition to the aggregated statement memory consumption value exceeds a total statement execution memory limit indicating a total amount of memory that may be allocated to all database operations associated with statement execution in a secondary database system, and denying the requested allocation of memory.

Abstract: Receiving a statement including requests for database operations in a secondary database system storing data replicated from a primary database system by replaying transaction output generated by the primary database system; responsive to receiving the statement, requesting an allocation of memory from the secondary database system to support the requested database operations; generating an aggregated statement memory consumption value based on the amount of memory consumed by all statements executing in the secondary database system that are not associated with replaying the transaction logs; determining that the requested allocation of memory in addition to the aggregated statement memory consumption value exceeds a total statement execution memory limit indicating a total amount of memory that may be allocated to all database operations associated with statement execution in a secondary database system, and denying the requested allocation of memory.

Abstract: Replicating a tenant database includes receiving at a source system a first request from a target system for replicating a first tenant database of the source system, which includes one or more first servers. Characteristics of the one or more first servers are sent to the target system to generate at the target system a second tenant database including one or more second servers. Each second server corresponds to one first server and has the same characteristics as the corresponding first server. Information from each first server is replicated, in an asynchronous mode, to the corresponding second server through a communication channel that is established between each first server and the second server. Upon receiving a second request for stopping the replication, a synchronous mode of processing statements from client applications of the first tenant database is entered. Related apparatus, systems, techniques and articles are described.

Abstract: A computer implemented method is provided comprising receiving a group of transaction logs from a first database, allocating transaction logs from the group of transaction logs to a first queue and to a second queue, generating an end-of-group transaction log indicative of an end of the group of transaction logs, allocating the end-of-group log to the first queue and the second queue; replaying transaction logs from the first queue including the end-of-group transaction log allocated to the first queue, replaying transaction logs from the second queue including the end-of-group transaction log allocated to the second queue; and changing visibility of one or more transactions in response to replaying the end-of-group transaction log allocated to the first queue and the end-of-group transaction log allocated to the second queue. Related apparatus, systems, techniques and articles are also described.