Abstract: In a mirrored database system, a careful write of intentions to perform file system actions is recorded in a persistent file system objects table that is flushed to disk prior to the actions being taken. The table durably and accurately records identities of file system objects that were in use by the database to facilitate creation and deletion of physical file directories and files on a database during crash recovery and during mirror resynchronize. In the event of a failure, crash recovery may quickly and easily identify file system objects which need to be cleaned up by reference to the persistent file system objects table. Similarly, resynchronization of the mirror database can be performed quickly by referring to the persistent file system table data to detect changes since the last database checkpoint.

Abstract: In a mirrored database system, a careful write of intentions to perform file system actions is recorded in a persistent file system objects table that is flushed to disk prior to the actions being taken. The table durably and accurately records identities of file system objects that were in use by the database to facilitate creation and deletion of physical file directories and files on a database during crash recovery and during mirror resynchronize. In the event of a failure, crash recovery may quickly and easily identify file system objects which need to be cleaned up by reference to the persistent file system objects table. Similarly, resynchronization of the mirror database can be performed quickly by referring to the persistent file system table data to detect changes since the last database checkpoint.

Abstract: In a database cluster comprising a plurality of mirrored database segments, a mirror database pair comprising a primary database and a mirror database are maintained substantially consistent by writing changes resulting from transactions to page data in parallel to the primary database and to the mirror database. Changes are sent to the mirror database over a network using network communications. Transaction logs are also written to the primary and mirrored databases in parallel, the transaction logs being sent to the mirror database using network communications. Bulk load changes resulting from transactions are written in parallel over the network to the primary database and the mirror database without writing the changes to a transaction log. In the event of a failure, resynchronization of the mirror database can be performed quickly while avoiding a lengthy ongoing redo process on the mirror database.

Abstract: In a mirrored database system, mirror resynchronization of bulk load and append-only tables during ongoing transactions is optimized for quick repair and high availability by catching up any changes to primary database tables that have not been made to mirror database tables during the transaction itself, and making changes due to ongoing transactions when the databases are synchronized to the resynchronization process.

Abstract: In a mirrored database system, a careful write of intentions to perform the system actions is recorded in a persistent file system objects table that is flushed to disk prior to the actions being taken. The table durably and accurately records identities of file system objects that were in use by the database to facilitate creation and deletion of physical file directories and files on a database during crash recovery and during mirror resynchronize. In the event of a failure, crash recovery may quickly and easily identify file system objects which need to be cleaned up by reference to the persistent file system objects table. Similarly, resynchronization of the mirror database can be performed quickly by referring to the persistent file system table data to detect changes since the last database checkpoint.

Abstract: In a mirrored database system, mirror resynchronization of fixed length pages is optimized for quick repair and high availability by identifying those lost page changes that must be made for resynchronization and ignoring other duplicate changes. Essential pages are identified using log sequence numbers (LSNs) to locate the most current version of a changed page, and other lower valued LSNs of less current versions of that page are eliminated as having changes that are duplicated in the current version of the page. Page changes since the last database checkpoint before losing mirror synchronization and the current LSN of the transaction log are identified as possibly necessary changes to be made.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A method, article of manufacture, and apparatus for recovering databases. In some embodiments, this includes switching an active segment to a resynchronization mode, receiving a change tracking log, determining a data block based on the change tracking log, and resynchronizing the determined data block with a non-active segment. In some embodiments, writes performed on the active segment are synchronized with the non-active segment.

Abstract: In a mirrored database system, good quality of service and high availability is afforded by minimizing the time required for suspension of operations to transition between mirror states, and by keeping track of changes made to a primary database while the mirror database was out of communications so that a later mirror resynchronization process can quickly catch up the mirror database by making only the lost changes.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A method, article of manufacture, and apparatus for recovering databases. In some embodiments, this includes switching an active segment to change tracking mode, intercepting write related changes on the active segment while in the change tracking mode, populating a change tracking log based on the intercepted write related changes, and storing the populated change tracking log in a storage device. In some embodiments, the storage device is memory. In some embodiments, the change tracking log if flushed from memory to disk.

Abstract: In a mirrored database system, mirror resynchronization of fixed length pages is optimized for quick repair and high availability by identifying those lost page changes that must be made for resynchronization and ignoring other duplicate changes. Essential pages are identified using log sequence numbers (LSNs) to locate the most current version of a changed page, and other lower valued LSNs of less current versions of that page are eliminated as having changes that are duplicated in the current version of the page. Page changes since the last database checkpoint before losing mirror synchronization and the current LSN of the transaction log are identified as possibly necessary changes to be made.

Abstract: In a mirrored database system, mirror resynchronization of bulk load and append-only tables during ongoing transactions is optimized for quick repair and high availability by catching up any changes to primary database tables that have not been made to mirror database tables during the transaction itself, and making changes due to ongoing transactions when the databases are synchronized to the resynchronization process.

Abstract: In a database cluster comprising a plurality of mirrored database segments, a mirror database pair comprising a primary database and a mirror database are maintained substantially consistent by writing changes resulting from transactions to page data in parallel to the primary database and to the mirror database. Changes are sent to the mirror database over a network using network communications. Transaction logs are also written to the primary and mirrored databases in parallel, the transaction logs being sent to the mirror database using network communications. Bulk load changes resulting from transactions are written in parallel over the network to the primary database and the mirror database without writing the changes to a transaction log. In the event of a failure, resynchronization of the mirror database can be performed quickly while avoiding a lengthy ongoing redo process on the mirror database.

Abstract: In a mirrored database system, good quality of service and high availability is afforded by minimizing the time required for suspension of operations to transition between mirror states, and by keeping track of changes made to a primary database while the mirror database was out of communications so that a later mirror resynchronization process can quickly catch up the mirror database by making only the lost changes.

Abstract: In a mirrored database system, a careful write of intentions to perform file system actions is recorded in a persistent file system objects table that is flushed to disk prior to the actions being taken. The table durably and accurately records identities of file system objects that were in use by the database to facilitate creation and deletion of physical file directories and files on a database during crash recovery and during mirror resynchronize. In the event of a failure, crash recovery may quickly and easily identify file system objects which need to be cleaned up by reference to the persistent file system objects table. Similarly, resynchronization of the mirror database can be performed quickly by referring to the persistent file system table data to detect changes since the last database checkpoint.

Abstract: A fault tolerant computer system distributes audit trail files containing audit records, across an arbitrary number of disk volumes. After one audit trail file becomes full, audit records are directed toward a next audit trail file stored on a different disk volume. Storage of newly generated audit rotates through the disk volumes in round-robin fashion. Full audit trail files are eventually archived and their space becomes available again for renaming and storage of newly generated audit records. The number of audit records available for on-line recovery after a failure is not limited to the storage capacity of any single disk volume. Furthermore, there is no contention for disk access between archiving of full audit trail files and storage of newly generated audit records.

Abstract: System-critical files are protected from being inadvertently modified or deleted by placing them in a Reserve name space of storage that requires any process seeking modifying access to the Reserve name space to have a "Right" to do so. The right to modifying access is garnered by a process first making a call to a system library procedure that causes a memory-stored data structure associated with the calling process to be modified, identifying the process as one with a Right to make modifying access to the Reserve name space. Any attempt to modify, delete, or create any file residing in the Reserve name space without the Right will be refused.

Abstract: A fault tolerant computer system distributes audit trail files containing audit records, across an arbitrary number of disk volumes. After one audit trail file becomes full, audit records are directed toward a next audit trail file stored on a different disk volume. Storage of newly generated audit rotates through the disk volumes in roundrobin fashion. Full audit trail files are eventually archived and their space becomes available again for renaming and storage of newly generated audit records. The number of audit records available for on-line recovery after a failure is not limited to the storage capacity of any single disk volume. Furthermore, there is no contention for disk access between archiving of full audit trail files and storage of newly generated audit records.

Abstract: A fault tolerant computer system distributes audit trail files containing audit records, across an arbitrary number of disk volumes. After one audit trail file becomes full, audit records are directed toward a next audit trail file stored on a different disk volume. Storage of newly generated audit rotates through the disk volumes in round-robin fashion. Full audit trail files are eventually archived and their space becomes available again for renaming and storage of newly generated audit records. The number of audit records available for on-line recovery after a failure is not limited to the storage capacity of any single disk volume. Furthermore, there is no contention for disk access between archiving of full audit trail files and storage of newly generated audit records.