Abstract: A database management system (DBMS) maintains a clone database in a clone space without storing an entire copy of the database and without requiring a snapshot function from an underlying storage device. This DBMS may receive a database command to access a data block of the clone database, and may determine whether the data block is stored in the clone space. If the data block is not stored in the local clone space, the DBMS may receive the data block from a backup copy of the database. If the database command comprises a write operation, the DBMS may perform the write operation to update the data block, and may store the updated data block in the clone space. Also, if the database command comprises a read operation, the DBMS may perform the read operation on the data block received from the backup copy of the database.

Abstract: A database management system (DBMS) maintains a clone database in a clone space without storing an entire copy of the database and without requiring a snapshot function from an underlying storage device. This DBMS may receive a database command to access a data block of the clone database, and may determine whether the data block is stored in the clone space. If the data block is not stored in the local clone space, the DBMS may receive the data block from a backup copy of the database. If the database command comprises a write operation, the DBMS may perform the write operation to update the data block, and may store the updated data block in the clone space. Also, if the database command comprises a read operation, the DBMS may perform the read operation on the data block received from the backup copy of the database.

Abstract: One embodiment of the present invention provides a resource scheduler for allocating a computer system resource, such as execution time within a processor, to database management system (DBMS) processes. The resource scheduler operates according to scheduling plans and policies. One or more plans may be configured and loaded with the DBMS. Each plan allocates the resource according to an associated policy but only one plan is active at a time. During operation of the DBMS, either or both of the active plan and policy may be exchanged for an alternate plan or policy without halting operation of the DBMS or the computer system.

Abstract: A scheduler for allocating a computer system resource, such as processor time, among processes (e.g., database processes) according to a plan. A scheduling plan may include multiple sub-plans, and each plan and sub-plan may include multiple classes of processes with associated weights or values. Within a plan, the resource is first allocated to the classes and/or sub-plans included in a first level of the plan according to their associated weights. Any unallocated portion of the resource is then allocated to classes/sub-plans in subsequent levels, in turn, according to their assigned weights. If a given class of processes is empty when the resource is allocated in a level including the class, the allocation that would have been allotted to the class may be carried over into the next level. An active scheduling plan may be dynamically replaced during system operations.