Abstract: A hierarchy may be explicitly or implicitly reflected in existing data maintained external to hierarchy structures. Such hierarchies are referred to herein as a “pre-existing hierarchies”. Techniques are described herein for capturing a pre-existing hierarchy in hierarchy structures. After a pre-existing hierarchy has been captured, there exist two independent sets of data that reflect the hierarchy: the external hierarchy definition and the internal hierarchy definition. Changing either hierarchy definition changes the hierarchy. Therefore, to maintain a consistent reflection of the hierarchy, the internal hierarchy definition must be modified in response to changes made to the external hierarchy definition, and the external hierarchy definition must be modified in response to changes made to the internal hierarchy definition. Various techniques are described for maintaining consistency between the two hierarchy definitions.

Abstract: One embodiment of the present invention provides a system that facilitates accessing communication queues using a public network. The system operates by first generating a message or messages at a client. The system then formats these messages in a publicly available format. Next, the system communicates the messages across the public network to a web server. The web server receives the messages and transforms the messages to a database specific format. The web server then passes the messages to a queue within a database server across a proprietary network. In one embodiment of the present invention, the system includes queue-to-queue propagation with exactly once guarantees and recovery from failures. In one embodiment of the present invention, the system includes transactional guarantees when a client accesses a queue.

Abstract: A database statement, such as a SQL text, reuses the execution plan compiled for a similar SQL text found in memory if the value of a system parameter is configured for cursor sharing among optimally shareable SQL texts and the SQL text is optimally shareable with the similar SQL text found in memory. Reuse also occurs if the value of a system parameter is configured for cursor sharing among all shareable SQL texts and the SQL text is suboptimally or optimally shareable with the similar SQL text found in memory. For SQL text that is non-shareable with a similar SQL text found in memory, no execution plan sharing takes place.

Abstract: Techniques are provided for sharing of flashback cursors by adding a time domain property to flashback cursors. This time domain property defines the range of flashback times for which the flashback cursor is valid. According to one embodiment, this “validity range” is closed at the lower bound and open at the upper bound. A subsequent flashback query can share an existing flashback cursor if the flashback time of the subsequent flashback query falls within the validity range of the existing flashback cursor. In one embodiment, the validity range of a flashback cursor is established based on times associated with indexes used to process the flashback query for which the flashback cursor was made. Consequently, an existing flashback cursor is less likely to be used by a subsequent flashback query when it would be inefficient to do so.

Abstract: One embodiment of the present invention provides a system that facilitates accessing communication queues using a public network. The system operates by first generating a message or messages at a client. The system then formats these messages in a publicly available format. Next, the system communicates the messages across the public network to a web server. The web server receives the messages and transforms the messages to a database specific format. The web server then passes the messages to a queue within a database server across a proprietary network. In one embodiment of the present invention, the system includes queue-to-queue propagation with exactly once guarantees and recovery from failures. In one embodiment of the present invention, the system includes transactional guarantees when a client accesses a queue.

Abstract: A method system and program for performing a query in which context and information including opcodes accompanies an execution plan for the query. The opcodes determine operations to retrieve a set of bind variables. The execution plan and context information shared by a plurality of application programs.

Abstract: A method and apparatus for efficient runtime memory access in a database is provided. A buffer pool is pre-allocated in cache. Buffers in the buffer pool are sized to accommodate average case queries and frequently executed queries. Buffers from the buffer pool are allocated to query working sets during runtime to reduce cache misses.

Abstract: A system and method for enabling a second database instance to more quickly process a request to execute a database statement that has previously been executed by a first database instance is described. In one embodiment, the method involves sending the database statement from the first database instance to the second database instance, and generating by the second database instance one or more structures needed to prepare the statement for execution, such as a parse tree and an execution plan for the statement. If at some point in the future, the second database instance receives a request to execute the same statement, the above structures can be used for execution, thereby eliminating the need for one or more potentially time-consuming operations, such as generation of a parse tree or execution plan for the statement.

Abstract: A system and method for enabling a second database instance to more quickly process a request to execute a database statement that has previously been executed by a first database instance is described. In one embodiment, the method involves sending the database statement from the first database instance to the second database instance, and generating by the second database instance one or more structures needed to prepare the statement for execution, such as a parse tree and an execution plan for the statement. If at some point in the future, the second database instance receives a request to execute the same statement, the above structures can be used for execution, thereby eliminating the need for one or more potentially time-consuming operations, such as generation of a parse tree or execution plan for the statement.

Abstract: Techniques and systems are disclosed for directly storing semistructured data in a database. According to one aspect, a client application reads data that comprises instances of a parent type. The client application invokes routines associated with the parent type. An array is created for storing instances of the parent type. These routines invoke routines associated with a child type of the parent type. An array is created for storing instances of the child type. The arrays are populated with values specified in the data. According to one aspect, some columns of the arrays may be populated with other values to be stored in hidden columns of database tables. The client application converts the arrays into a data stream that conforms to the format of the database's data blocks. The client application then streams the data to a database server, which writes the data blocks directly into one or more data blocks in the database.

Abstract: Described is a method and system for storing data into a database, where a determination is made if schema metadata that is used to load the data into the database already exists, and where the existing schema metadata is used to load the data into the database if the schema metadata already exists. If the appropriate schema metadata does not exist, then it is generated and cached so that a later load operation for the same schema type will not need to re-generate this information. In this way, the cost to generate the schema metadata is amortized over multiple load operations to load data of the same schema type. The approach is protocol neutral so that multiple different protocol-based loads can operate with the same schema metadata information and load structures.

Abstract: Techniques and systems are disclosed for storing instances of an opaque type in a database according to a direct path loading approach. According to one aspect, an opaque type implementor registers, with a loader application, routines that the opaque type implementor implements. In response, the loader application associates the opaque type with the routines. The loader application reads data that comprises instances of the opaque type. The loader application determines which routines are associated with the opaque type. The loader application invokes the routines, which create an array for storing instances of the opaque type and populate the array with values specified in the data. The loader application converts the array into a data stream that conforms to the format of the database's data blocks. The loader application then streams the data to a database server, which writes the data directly into data blocks in the database.

Abstract: A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained.

Abstract: A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained.

Abstract: A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained.

Abstract: A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained.

Abstract: A buffered message queue architecture for managing messages in a database management system is disclosed. A “buffered message queue” refers to a message queue implemented in a volatile memory, such as a RAM. The volatile memory may be a shared volatile memory that is accessible by a plurality of processes. The buffered message queue architecture supports a publish and subscribe communication mechanism, where the message producers and message consumers may be decoupled from and independent of each other. The buffered message queue architecture provides all the functionality of a persistent publish-subscriber messaging system, without ever having to store the messages in persistent storage. The buffered message queue architecture provides better performance and scalability since no persistent operations are needed and no UNDO/REDO logs need to be maintained.

Abstract: A hierarchy may be explicitly or implicitly reflected in existing data maintained external to hierarchy structures. Such hierarchies are referred to herein as a “pre-existing hierarchies”. Techniques are described herein for capturing a pre-existing hierarchy in hierarchy structures. After a pre-existing hierarchy has been captured, there exist two independent sets of data that reflect the hierarchy: the external hierarchy definition and the internal hierarchy definition. Changing either hierarchy definition changes the hierarchy. Therefore, to maintain a consistent reflection of the hierarchy, the internal hierarchy definition must be modified in response to changes made to the external hierarchy definition, and the external hierarchy definition must be modified in response to changes made to the internal hierarchy definition. Various techniques are described for maintaining consistency between the two hierarchy definitions.

Abstract: One embodiment of the present invention provides a system that automatically sends a notification about a database event. The system operates by receiving a number of items, including a registration of a specified event-type, a subscription of a protocol for the notification, a format for the notification, and a list of recipients for the notification. The system then configures the database to send the notification about the specified event-type to the specified list of recipients in the specified format via the specified protocol. Adding this notification capability at the database-level enhances the functionality and interoperability of many applications as well as providing more robust and timely information to the appropriate audiences.

Abstract: A technique for database management includes receiving an indication of a selected scope of a trigger. The scope is selected from a plurality of scopes of database management. The scope can be on the level of an individual table, or a schema associated with a user, or the database itself, or a system of databases, among others. The technique also includes receiving an indication of a selected event that belongs to the set of one or more events associated with the selected scope. Trigger metadata is stored that identifies both the selected scope and the selected event. A technique is also described for executing a process in this database management system. Flags indicative of one or more applicable events of the selectable events are loaded into a private cache of the process and checked when a new event occurs.