Abstract: Commit latency is reduced for pending transactions. The transactions are replicated from a source database to a target database by a replication engine. The pending transaction is incomplete in either the source or the target database. A transaction pattern table is provided that includes a plurality of records, each record being defined by a transaction pattern identifier. Each record includes a transaction pattern and a metric of occurrence of the transaction pattern. A comparison is made of the series of one or more transaction steps or operations of a pending transaction to the transaction patterns in the transaction pattern table, and a subset of transaction patterns in the transaction pattern table are identified that are potential candidates for matching the pending transaction. The pending transaction is categorized using the metric of occurrence of the transaction pattern for each transaction pattern in the subset of transaction patterns.

Abstract: An automated method and apparatus are provided for comparing a first database and a second database that are intended to be kept in synchronization with each other. Applications process changes that are posted to the first database and the second database. Changes made to the first database are applied to the second database, and vice-versa. Changes made to the first database resulting from changes posted to the first database are collected into a first change log. Changes made to the second database resulting from changes posted to the second database are collected into a second change log. Representations of the changes that correspond to the same respective changes in the change logs are compared with each other. Corrective action is performed when the comparison indicates that the corresponding representations of the changes in the first change log and the second change log do not match.

Abstract: Hung transactions which are completed within a transaction processing system are resolved. The transactions are replicated from a source database to a target database by a replication engine. The hung transaction is incomplete in either the source or the target database. A transaction pattern table is provided that includes a plurality of records, each record being defined by a transaction pattern identifier. Each record includes a transaction pattern and a metric of occurrence of the transaction pattern. A comparison is made of the series of one or more transaction steps or operations of a hung transaction to the transaction patterns in the transaction pattern table, and a subset of transaction patterns in the transaction pattern table are identified that are potential candidates for matching the hung transaction. The hung transaction is categorized using the metric of occurrence of the transaction pattern for each transaction pattern in the subset of transaction patterns.

Abstract: A method and apparatus are provided for avoiding target database constraint violations in a database replication system. The database replication system includes a source database and a target database, wherein target database transactions automatically abort due to constraint violations. Each database has one or more tables and at least one of the target database tables has one or more constraints. The database replication system replicates source database transactions. For each target database transaction corresponding to a replicated source database transaction, changes made at the source database are replicated to the target database. When it is detected that a replicated change causes a constraint violation as a result of one or more of the target database tables having one or more constraints, the applying of the database change to the target database of the database change is deferred and the database change is posted to an electronic list.

Abstract: An automated method and apparatus are provided for comparing a source database and a target database that are intended to be kept in synchronization with each other. An application processes database changes that are posted to the source database and replicated to the target database. The source database and the target database are made up of blocks of data. Blocks of data from the source database having database changes are collected. These blocks of data are replicated to the target database. Blocks of data from the target database that correspond to the blocks of data from the source database having database changes are read. Representations of the blocks of data from the source database having database changes are compared to representations of blocks of data from the target database that correspond to the blocks of data from the source database having database changes.

Abstract: An automated method and system are provided for comparing a source database and a target database that are intended to be kept in synchronization with each other. An application processes transactions that are posted to the source database and replicated to the target database. Before images of changes made to records or rows of the source database resulting from transactions posted to the source database into a first change log are collected. The before images of changes made to records or rows of the source database are replicated to the target database. Current images of records or rows of the target database that correspond to the before images of changes made to records or rows of the source database are read. Representations of the before images of changes made to records or rows of the source database are compared with representations of the current images of records or rows of the target database that correspond to the before images of changes made to records or rows of the source database.

Abstract: Methods and apparatus are provided for processing a transaction that has been aborted on a source system. Transactions are completed within a transaction processing system, and the transactions are replicated from a source database to a target database by a replication engine. Each transaction is a series of one or more transaction steps or operations. The aborted transaction on the source system was replicated and is a pre-committed transaction on the target database. Transaction pattern data in a transaction pattern table is used to predict when a pre-committed transaction is an erroneously committed transaction. The pre-committed transaction is reversed on the target database when the prediction indicates that the pre-committed transaction was erroneously committed.

Abstract: Methods and apparatus are provided to fully process an incomplete transaction which is incomplete in either a source database or a target database. Transactions are completed within a transaction processing system that includes a non-static application. The non-static application has a transaction mix that varies over its life cycle. The transactions are replicated from the source database to the target database by a replication engine. Each transaction is a series of one or more transaction steps or operations. A plurality of transaction pattern tables are provided, and one of the transaction pattern tables are selected for use in the process depending upon a time of day or a transaction mix.

Abstract: An automated method and system are provided for comparing a source database and a target database that are intended to be kept in synchronization with each other. An application processes transactions that are posted to the source database and replicated to the target database. Before images of changes made to the source database resulting from transactions posted to the source database are collected into a first change log and then replicated to the target database. Before images of changes made to the target database resulting from replication are collected into a second change log. Representations of the before images of changes in the first change log are compared with representations of the before images of changes in the second change log that correspond to the same respective changes that were made to the source database and replicated to the target database.

Abstract: An automated method is provided for use when replacing a currently operating data replication engine in a first system with a new data replication engine in the first system in a bidirectional data replication environment. The currently operating data replication engine in the first system and the new data replication engine in the first system replicates first database transactions from an audit trail of a first database in the first system to a second database in a second system. The new data replication engine in the first system generating a list of active database transactions in the first system, and sends the list of active database transactions to the new data replication engine in the second system as a first token.

Abstract: Methods and apparatus are provided to fully process an initially incomplete replicated and committed transaction. A transaction pattern table is provided that includes a plurality of records, each record being defined by a transaction pattern identifier. Each record includes a transaction pattern and a metric of occurrence of the transaction pattern. An incomplete transaction is automatically compared to the transaction patterns in the table and a subset of transaction patterns in the table are identified that are potential candidates for matching the incomplete transaction. The incomplete transaction is categorized using the metric of occurrence of the transaction pattern for each transaction pattern in the subset. The categorization predicts when all steps or operations of the transaction which have completed in the source database have been replicated, and the incomplete transaction is committed based on this prediction.

Abstract: Source database precommitted transactions are resolved in a target database of a database replication system when selected source database precommitted transactions are subsequently aborted in the source database.

Abstract: An automated method is provided for replacing a currently operating data replication engine with a new data replication engine. The currently operating data replication engine replicates source database transactions including any new source database transactions committed in an audit trail of the source database before the currently operating data replication engine stops replicating. All new source database transactions that the currently operating data replication engine has not completed replicating are joined. The currently operating data replication engine is stopped when all of the source database transactions that were not joined have completed replicating. All joined transactions are then voted to be committed and are replicated. The new data replication engine replicates all new source database transactions started after the currently operating data replication engine stops.

Abstract: Target database constraint violations are potentially resolved in a database replication system by replacing, converting, or removing deferred database changes.

Abstract: An automated method and system are provided for comparing a source database and a target database that are intended to be kept in synchronization with each other. An application processes transactions that are posted to the source database and replicated to the target database. Changes made to the source database resulting from transactions posted to the source database are collected into a first change log and then replicated to the target database. Changes made to the target database resulting from replication are collected into a second change log. The changes in the first change log are compared with representations of the changes in the second change log that correspond to the same respective changes that were made to the source database and replicated to the target database. Corrective action is performed when the comparison indicates that the representations of the changes in the first change log do not match the representations of the changes in the second change log.

Abstract: An automated method is provided for replacing a currently operating data replication engine with a new data replication engine. The currently operating data replication engine replicates source database transactions including any new source database transactions committed in an audit trail of the source database before the currently operating data replication engine stops replicating. A list of active database transactions is generated and recorded as a first token in the audit trail. The currently operating data replication engine is stopped when all of the database transactions in the first token have completed. The new data replication engine is started and positioned to begin processing source database transactions in the audit trail of the source database at a beginning position that is located at or prior to the position of the first token in the audit trail.

Abstract: A system and method of backing up an online database to a storage device is provided wherein the online database is actively changed by one or more applications. The backed up online database is then subsequently restored. The online database is backed up by copying the online database to the storage device, and during the copying of the online database, writing changes that are made to the online database to a change log for the portion of the online database that has already been copied to the storage device, and not writing changes that are made to the online database to the change log for the portion of the online database that has not yet been copied to the storage device. The changes in the change log are applied to the storage device by rolling the change log backwards, and applying only the most recent change contained in the change log for each data item in the storage device.

Abstract: A system and method of backing up an online database to a storage device is provided wherein the online database is actively changed by one or more applications. The backed up online database is then subsequently restored. The online database is backed up by copying the online database to the storage device, and during the copying of the online database, writing changes that are made to the online database to a change log for the portion of the online database that has already been copied to the storage device, and not writing changes that are made to the online database to the change log for the portion of the online database that has not yet been copied to the storage device. The online database is then restored by loading the backed up online database to a target database, and applying the changes in the change log to the target database by rolling the change log backwards, and applying only the most recent change contained in the change log for each data item in the target database.

Abstract: An extractor and an applier of a database replication system are configured to perform the functions of resolving target database constraint violations for replicated database transactions. The extractor replicates changes made at the source database to the target database. An applier immediately applies the changes to the target database that do not cause a constraint violation. The applier also performs the remaining functions, including detecting database changes that cause constraint violations, subsequent processing of these detected database changes, and performing a commit for the database transaction when the constraint violations are resolved.

Abstract: Methods and apparatus are provided to categorize and process an incomplete transaction. A transaction pattern table is provided that includes a plurality of records, each record being defined by a transaction pattern identifier. Each record includes a transaction pattern and a metric of occurrence of the transaction pattern. An incomplete transaction is automatically compared to the transaction patterns in the table and a subset of transaction patterns in the table are identified that are potential candidates for matching the incomplete transaction. The incomplete transaction is categorized using the metric of occurrence of the transaction pattern for each transaction pattern in the subset. The incomplete transaction is then processed using the categorization of the incomplete transaction.