Abstract: Non-mutating tree-structured file identifiers are used to identify files stored in a file system. Each of multiple files in the file system has a corresponding non-mutating file identifier, and these file identifiers are assigned and maintained using a tree structure.

Abstract: A method, apparatus, system, and signal-bearing medium that in an embodiment, store a reason identifier in rows in a database. The reason identifier identifies the most recent change to the rows. The content of the rows that existed prior to the change are stored in journal records. In response to an undo command, the most-recent instance of each record identifier in the records associated with the reason identifier are found in the journal and moved to the database in reverse time sequence order. In an embodiment, a promote operation requests moving the change upwards in a sequence, from a source version to a target version of the database. In response to the promote operation, a determination is made whether rows with the same row identifiers but a different reason identifier exist in a target version of the database, but the different reason identifier is complete.

Abstract: A system, method, and computer readable medium for preserving information in time variant data schemas are disclosed. The method includes determining if at least one modification request associated with a database schema has been received. In response to the modification request being received, a metadata table associated with the database schema is updated to include at least one entry associated with the modification request. The entry identifies an instance in time when an action associated with the modification request was performed.

Abstract: In a space incremental garbage collector, remembered set information for a region is stored in a set of fixed-size data structures, each of which has a representation of the information and a level of precision that differs from other data structures in the set. Remembered set information for each other region is placed in a data structure based on the density of inter-region references between the region and the other region. The remembered set information for the other region is moved from one data structure to another data structure when the density of inter-region references between the region and the other changes. Some of the data structures use bit arrays to store the information and these arrays can be combined with bit arrays produced by the collector to facilitate the identification and removal of stale remembered set entries.

Abstract: A method, apparatus, system, and signal-bearing medium that, in an embodiment, receive a constraint command that specifies a parent table, a primary key in the parent table, a child table, and a foreign key in the child table, and enforce that all values for the primary key in the parent table are present in the foreign key in the child table. In an embodiment, the enforcing may include receiving an insert command, wherein the insert command specifies a target key, a target value for the target key, and a target table; determining whether the target table matches the parent table and whether, within a transaction that includes the insert command, the child table includes at least one row with a foreign key value that equals the target value of the primary key; inserting the target value in the target table if the determining is true; and returning an error otherwise.