摘要:
A multi-tier database system is modified such that a middle-tier application server (EJB server) and a database server run on the same host computer and communicate via shared-memory interprocess communication. The system includes a database (e.g., JDBC) driver thread that attaches to the database server, specifically by attaching to the database server's shared memory segment. Operation of the JDBC driver is modified to provide direct access between the middle tier (i.e., EJB server) and the database server, when the two are operating on the same host computer.
摘要:
A database system providing methodology for extended memory support is described. In one embodiment, for example, a method is described for extended memory support in a database system having a primary cache, the method comprises steps of: creating a secondary cache in memory available to the database system; mapping a virtual address range to at least a portion of the secondary cache; when the primary cache is full, replacing pages from the primary cache using the secondary cache; in response to a request for a particular page, searching for the particular page in the secondary cache if the particular page is not found in the primary cache; if the particular page is found in the secondary cache, determining a virtual address in the secondary cache where the particular page resides based on the mapping; and swapping the particular page found in the secondary cache with a page in the primary cache, so as to replace a page in the primary cache with the particular page from the secondary cache.
摘要:
A database system providing self-tuned parallel database recovery is described. In one embodiment, for example, in a database system, a method is described for performing recovery operations using an optimal number of recovery threads, the method comprises steps of: (a) spawning an initial recovery thread to perform recovery operations; (b) measuring I/O (input/output) performance with the initial recovery thread; (c) spawning a subsequent recovery thread to perform recovery operations; (d) measuring I/O performance with the subsequent recovery thread; and (e) as long as I/O performance does not degrade beyond a preselected percentage, repeating steps (c) and (d) for spawning a desired number of additional recovery threads. In another embodiment, the database system auto-tunes the cache during performance of database recovery operations to optimize the performance of recovery operations.
摘要:
A database system providing self-tuned parallel database recovery is described. In one embodiment, for example, in a database system, a method is described for performing recovery operations using an optimal number of recovery threads, the method comprises steps of: (a) spawning an initial recovery thread to perform recovery operations; (b) measuring I/O (input/output) performance with the initial recovery thread; (c) spawning a subsequent recovery thread to perform recovery operations; (d) measuring I/O performance with the subsequent recovery thread; and (e) as long as I/O performance does not degrade beyond a preselected percentage, repeating steps (c) and (d) for spawning a desired number of additional recovery threads. In another embodiment, the database system auto-tunes the cache during performance of database recovery operations to optimize the performance of recovery operations.
摘要:
A database system providing improved methods for asynchronous logging of transactions is described. Log records are created describing changes to a database made by a transaction. When a command committing changes to the database for the transaction is received, a logging request is placed in a queue. An asynchronous logging service removes requests from the queue and transfers log records from the transaction to a shared cache. The shared cache stores log records before they are written to the transaction log. The logging service writes log pages containing log records for the transaction from the cache to the transaction log. After all log pages in the cache for the transaction have been written to the transaction log, changes to the database made by the transaction can be committed to the database.
摘要:
A database system providing methodology for extended memory support is described. In one embodiment, for example, a method is described for extended memory support in a database system having a primary cache, the method comprises steps of: creating a secondary cache in memory available to the database system; mapping a virtual address range to at least a portion of the secondary cache; when the primary cache is full, replacing pages from the primary cache using the secondary cache; in response to a request for a particular page, searching for the particular page in the secondary cache if the particular page is not found in the primary cache; if the particular page is found in the secondary cache, determining a virtual address in the secondary cache where the particular page resides based on the mapping; and swapping the particular page found in the secondary cache with a page in the primary cache, so as to replace a page in the primary cache with the particular page from the secondary cache.