Abstract: A transaction system implemented on a server machine for maintaining consistency in an information system supporting asynchronous transactions. The information system includes a database shared among a plurality of users and implemented on a client machine. The transaction system is invoked at run-time for a transaction where the transaction includes one or more subtransaction steps. The transaction system includes a graphical user interface for receiving a user defined isolation level selection for executing a transaction between the server machine and the database or application, a persistent service for storing object state information for each object affected in the execution of each subtransaction step and a state verification service for verifying the state of each object affected by a subtransaction step to verify the state of the object is the same as a last time the object was seen in the transaction.

Abstract: Computer systems and computer implemented methods are provided for managing memory in a database management system. The computer memory is partitioned into a plurality of buffer caches, each of which is separately addressable. One buffer cache is set aside as a default buffer cache, while the other buffer caches are reserved for specific data objects meeting certain predefined criteria. Those objects meeting the predefined criteria are stored in reserved buffer caches where they are likely to remain for a relatively long period of time (in comparison to data objects stored in the default buffer caches). A buffer cache may have a plurality of memory pools, each of which contains multiple storage blocks. The storage blocks in a given memory pool are identically sized, while the storage blocks in one memory pool are sized differently from the storage blocks in another memory pool.

Abstract: Database system and methods are described for improving execution speed of database queries (e.g., for transaction processing and for decision support) by optimizing use of buffer caches. The system includes an Optimizer for formulating an optimal strategy for a given query. More particularly, the Optimizer communicates with a Buffer Manager before it formulates the query plan. For instance, the Optimizer may query the Buffer Manager for the purpose of determining whether the object of interest (e.g., table or index to be scanned) exists in its own buffer cache (i.e., whether it has been bound to a particular named cache). If the object exists in its own cache, the Optimizer may inquire as to how much of the cache (i.e., how much memory) the object requires, together with the optimal I/O size for the cache (e.g., 16K blocks). Based on this information, the Optimizer formulates a query strategy or plan with "hints," which are ultimately passed to the Cache or Buffer Manager.

Abstract: Computer systems and computer implemented methods are provided for managing memory in a database management system. The computer memory is partitioned into a plurality of buffer caches, each of which is separately addressable. One buffer cache is set aside as a default buffer cache, while the other buffer caches are reserved for specific data objects meeting certain predefined criteria. Those objects meeting the predefined criteria are stored in reserved buffer caches where they are likely to remain for a relatively long period of time (in comparison to data objects stored in the default buffer caches). A buffer cache may have a plurality of memory pools, each of which contains multiple storage blocks. The storage blocks in a given memory pool are identically sized, while the storage blocks in one memory pool are sized differently from the storage blocks in another memory pool.