International Business Machines Corporation

Sabine Perathoner-Tschaffler

Einar Lueck

Felix O Beier

Dennis Butterstein

Daniel Martin

Knut Stolze

Andreas Brodt

Bjoern Broll

Jens Müller

Stefan Renner

Antje Dengler

Brigitte Gößler

Aspects of the present disclosure relate to recovery of a target database system. The method comprises receiving multiple batches of database transactions to form the target database system. The method further comprises generating a single recovery bookmark before beginning processing of a current batch, wherein the single recover bookmark comprises: an earliest open entry for a previous batch, a latest commit entry for the previous batch, an earliest open entry for the current batch, a latest commit entry for the current batch, a transactional identifier, and list of tables to be processed; performing the sequence of database transactions; replacing the list of tables from the single recovery bookmark with a flag value upon completion; detecting a fault condition during the performance of the sequence of database transactions; recovering the target database system using the single recovery bookmark; and resuming the sequence of database transactions.

Recovery of a target database system

The present disclosure relates to a computer implemented method for data synchronization in a data analysis system. The data analysis system comprises a source and target database system. The method comprises: receiving a change record describing an operation performed on a data record in the source database system. The change record may be read for determining a value of a distribution key of the data record. The value of the distribution key may be used for selecting a target database node of the target database system where the operation is to be performed. A direct connection may be established to the selected target database node and the change record may be provided to the selected target database node through the direct connection.

Data distribution in data analysis systems

A computer-implemented method for a crash recovery for linked databases may be provided. The linked databases comprise a source and related target database. Selected queries of the source database are transferred to the target database. The method comprises synchronizing selected portions of the source database with tables of an in-memory portion of target database and, storing persistently applied changes to the in-memory target database portion asynchronously and persistently. Upon a database crash of the target database system, the method also comprises restoring, the in-memory target database portion with the latest snapshot available, and applying, changes from the source database recovery log file that have a later timestamp than the latest snapshot available in the persistent target database storage of the in-memory target database portion.

Asynchronous persistency of replicated data changes in a database accelerator

A computer implemented method comprises receiving at least one log record. A type of operation performed in a source database system may be determined based on the log record. Based on the type of operation, an update strategy may be selected from a set of pre-defined update strategies, wherein the update strategy specifies a sequence of replication operations to be performed in order to apply changes described in the at least one log record to a target database system.

Data synchronization in a data analysis system

In an approach to improve online database replication by automating the upgrading of a database replications system online. Additionally, embodiments of the present invention stop an upgrade using a first incremental update strategy on data of a source database, identify an earliest open transaction from a first database to a second database, and identify a last committed log record identifier. Further, embodiments of the present invention execute an adaptive apply strategy on transactions including the earliest open transaction until the last committed log record identifier is reached by the adaptive apply strategy, and resume, by upgrade controller, the upgrade with a second incremental update strategy.

Automated online upgrade of database replication

A computer-implemented method for a crash recovery for linked databases may be provided. The linked databases comprise a source database and a related target database, and selected portions of content of tables of the source database are synchronized with respective portions of the content of the tables of the target database. Thereby, selected queries against a database management system comprising the source database are transferred to a database management system comprising the target database for processing. And the method also comprises synchronizing the portions of the content of the selected tables in the target database with the portions of the content of the selected tables in the source database by reading entries of a recovery log file relating to the source database and applying the read entries to the target database.

Volatile database caching in a database accelerator

The present disclosure relates to a method for data replication in a data analysis system (). A source database system () of the data analysis system () comprises a transaction log () storing log records generated by database transactions. The method comprises in response to determining () that a received log record is generated by a database transaction that rolls back a change of another database transaction whose log records are buffered in at least one record buffer, data indicative of a log record generated by the other database transaction buffering () in the compensation buffer tag data. The tag data may be used () for replicating to a target database system of the data analysis system buffered log records of the record buffer which are not marked as compensation records.

Data replication in a data analysis system

A method comprises receiving a stream of change log records from a source database system; generating change statistics based on a number of pending changes per table partition according to the change log records; estimating, based on performance statistics, a first amount of time for applying the pending changes to a target database system using an incremental update path; estimating, based on the performance statistics, a second amount of time for applying the pending changes to the target database using a bulk update path; dynamically selecting, based on comparison of the first amount of time with the second amount of time, one of the incremental update path and the bulk update path for applying the pending changes to the target database system; and applying the pending changes to the target database system using the selected update path.

Dynamic selection of synchronization update path

Approaches presented herein enable replicating data records between a source database and a target database. More specifically, for a batch of change records in a table received from the source database, a first estimated replication duration needed to apply the batch as a bulk change to the target is determined. For the same batch, a second estimated replication duration needed to apply a set of changes in a single row of the table to the target is determined based on time penalties for each column in the row. A threshold quantity of rows at which the first duration equals a summed total of second durations for the quantity is calculated. The bulk change is selected if a number of rows in the batch exceeds the threshold. Applying change records singly is selected if the number of rows in the batch is less than the threshold.

Dynamic selection of data apply strategy during database replication

A computer-implemented method for controlling a system is provided. The system includes a source database and a target database. The system can asynchronously replicate data changes of at least one part of the source database to the target database. This asynchronous replication includes evaluating, by a capture engine, a log of the source database for identifying any un-replicated data changes of the at least one part of the source database, transferring the identified data changes to an apply engine, and applying, by the apply engine, the transferred data changes to the target database.

Controlling a multi-database system

The invention relates to computer-implemented method for updating a target table with changes introduced into a source table. New data records are stored into partitions of the source table. An incremental update module copies the new data records from the source table into the target table, thereby assigning a new target partition ID contained within a first value domain to each copied data record. A view specifies a set of visible partition IDs as a union of the first value domain and of a current target partition ID set and allows the execution of database queries selectively on target table partitions having assigned a target partition ID that is element of the visible partition ID set. A batch update module performs an atomic batch update operation that comprises copying partitions of the source table into a respective new partition in the target table.

Updating a table using incremental and batch updates

Disclosed herein are methods for receiving a command for adding or removing a resource in a database and acquiring an exclusive lock for the database in response the command. In response to obtaining the exclusive lock, the method comprises determining a first number indicating the number of resources currently existing in the database and a second number indicating the number of resources subject to concurrent further commands for adding or removing a resource; comparing the first and the second number for determining whether the received command will remove the last existing resource or add a first resource to the database; and obtaining an exclusive or a shared lock for the received command in dependence on the determination. The method further includes releasing the exclusive lock for the database and adding or removing the resource while holding the lock obtained for the received command.

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Nufringen, Germany

Sabine Perathoner-Tschaffler