A transaction protocol is described that allows a database transaction to begin as a local, lightweight transaction without involving a distributed transaction coordinator and then be promoted to a distributed transaction only when required, e.g. when more than one database connection is required. A promotable enlistment allows a first resource to begin processing a promotable transaction. If the resource is notified that the transaction is being promoted to a distributed transaction, the resour...

One or more indexes are built on data (concurrent with manipulation of data) wherein the index build operation is done without restricting the manipulation of data. The index is brought to consistency with the data based upon processing recovery log records to simulate index manipulations during data insert, update, or delete operations.

A mechanism and system are described for either releasing held resources in the case of a deadlock or to postpone requests for resources when a potential deadlock is detected. One technique involves a three pass algorithm for selecting a candidate, where the candidate is either a possessory entity or resource is used. The three passes are as follows: (1) determining the subset of candidates, which have the CAN-BE-VICTIM flag set on; (2) If pass one results in a subset with more than one candidat...

A method and an apparatus for recording data with pseudo-merge are provided. The apparatus comprises a storage medium for storing a first and a second files and a File Allocation Table (FAT) for recording a first start position and a first end position for the first file and recording a second start position and a second end position for the second file. The method modifies the first end position of the first file to be the second start position of the second file so as to merge the first and se...

A system, method, apparatus, means and computer program code for utilizing multiple log queues in a database management system are provided. In some embodiments, processing includes receiving a first log record at a first log queue and a second log record at a second log queue, associating a log queue identifier with each of the first and second log records, and writing the first and second log records to a data log. Pursuant to some embodiments, at least a third log queue is provided.

A method and system are provided to enable restoration of a base table and associated catalog table from a database. Table names and table identifiers are copied to a header of a storage media during a backup of the database. When a restore of a designated table is requested, table identifier data is extracted from the header of the storage media housing the backup of the database. Accordingly, the designated base table and associated catalog table(s) are restored from the storage media based up...

The present invention relates to a method and a computer program for concurrency control for a secondary index (13) wherein many deadlocks are avoided by means of a selective locking strategy and by means of allowing index records (14) of the secondary index to contain some keys to many but never too few. When keys are read from the secondary index (13) it is thus possible to read some keys that may be irrelevant. However, such irrelevant keys are sorted out by means of checking against the corr...

Techniques are described herein for returning a repository to a prior state. The repository may be, for example a database, and the prior state may be, for example the consistent state that the database had at a particular point in time in the past. When a operator-caused error has been introduced to the database by changes made by an already-committed transaction, the techniques described herein may be used to recover from the error by returning the database to a point in time prior to the comm...

A methodology wherein two different types of locks are used by a storage manager when multiple clients wish to access a particular redundantly-stored file. Simple byte-range based mutual exclusion (or mutex) locks are granted by the storage manager for data writes/updates to the file when the file is in the fault-free state, and individual readers/writers (R/W) locks are granted by the storage manager when the file is in the degraded state. No read locks are required of clients when the file obj...

The present invention is related to a method and system for preserving an original table schema for a table in a database system that supports dynamic table schema changes. The method and system includes storing the original table schema for the table in a designated table prior to performing a schema change on the table. By storing the original table schema in the designated table, a backup copy of the table that includes rows which are not self-describing can be used for data recovery.