Abstract: Disclosed is an approach to implement a multi-tenant DNS resolver for secure communications for a virtual cloud environment. The approach can perform split-horizon DNS forwarding via an intermediate customized DNS server.

Abstract: A database session in an active standby server on which an active standby database resides receives a DML statement. The session is suspended while the statement is redirected over a database link to a primary database on which the statement is executed. Information associated with execution of the statement is communicated to the session in the active standby server. Redo records describing changes to the contents of the primary database are applied to the active standby database and control is returned to the session. Prior to commitment of a transaction including the statement, a query directed to data to which the statement was directed is received at the active standby server from a client and executed on the active standby database absent use of a database link based on whether information associated with a database session associated with the client matches the information associated with execution of the statement.

Abstract: A container is a collection of schemas, objects, and related structures in a multitenant container database (CDB) that appears logically to an application as a separate database. Within a CDB, each container has a unique ID and name. The root database and every PDB is considered a container. PDBs isolate data and operations so that from the perspective of a user or application, each PDB appears as if it were a traditional non-CDB. A database management system that manages a container database is a container database management system (CDBMS). Data and metadata in the root database may include common schemas that make the functionality that users will often use available CDB-wide. To execute a query accessing a common schema, the common schemas may be accessed by sessions of a PDB without switching database contexts.

Abstract: A database session in an active standby server on which an active standby database resides receives a DML statement. The session is suspended while the statement is redirected over a database link to a primary database on which the statement is executed. Information associated with execution of the statement is communicated to the session in the active standby server. Redo records describing changes to the contents of the primary database are applied to the active standby database and control is returned to the session. Prior to commitment of a transaction including the statement, a query directed to data to which the statement was directed is received at the active standby server from a client and executed on the active standby database absent use of a database link based on whether information associated with a database session associated with the client matches the information associated with execution of the statement.

Abstract: Disclosed is a system, method, and computer program product that allows multiple partition schemes to be applied to a single object. Each scheme represents the same set of partitions, but the schemes may have different partition methods, different partition keys, and/or different partition bounds.

Abstract: A database session in an active standby server on which an active standby database resides receives a DML statement. The session is suspended while the statement is redirected over a database link to a primary database on which the statement is executed. Information associated with execution of the statement is communicated to the session in the active standby server. Redo records describing changes to the contents of the primary database are applied to the active standby database and control is returned to the session. Prior to commitment of a transaction including the statement, a query directed to data to which the statement was directed is received at the active standby server from a client and executed on the active standby database absent use of a database link based on whether information associated with a database session associated with the client matches the information associated with execution of the statement.

Abstract: A container is a collection of schemas, objects, and related structures in a multitenant container database (CDB) that appears logically to an application as a separate database. Within a CDB, each container has a unique ID and name. The root database and every PDB is considered a container. PDBs isolate data and operations so that from the perspective of a user or application, each PDB appears as if it were a traditional non-CDB. A database management system that manages a container database is a container database management system (CDBMS). Data and metadata in the root database may include common schemas that make the functionality that users will often use available CDB-wide. To execute a query accessing a common schema, the common schemas may be accessed by sessions of a PDB without switching database contexts.

Abstract: A method and apparatus are provided for building and using a persistent XML tree index for navigating an XML document. The XML tree index is stored separately from the XML document content, and thus is able to optimize performance through the use of fixed-sized index entries. The XML document hierarchy need not be constructed in volatile memory, so creating and using the XML tree index scales even for large documents. To evaluate a path expression including descendent or ancestral syntax, navigation links can be read from persistent storage and used directly to find the nodes specified in the path expression. The use of an abstract navigational interface allows applications to be written that are independent of the storage implementation of the index and the content. Thus, the XML tree index can index documents stored at least in a database, a persistent file system, or as a sequence of in memory.

Abstract: Techniques are provided for diverting, to cloned metadata, live access to original metadata of an application container that is being concurrently upgraded. In an embodiment, a database server stores, within an application container of an application, original metadata that defines objects for use by pluggable databases of the application. The database server receives a maintenance request to adjust the original metadata. The database server creates, in response to receiving the maintenance request, a reference container that contains cloned metadata that is a copy of the original metadata. The database server receives, during or after creating the reference container, a read request to read one of the objects. The database server concurrently performs both of: executing the maintenance request upon the original metadata, and executing the read request upon the cloned metadata of the reference container.

Abstract: Disclosed is a system, method, and computer program product that allows multiple partition schemes to be applied to a single object. Each scheme represents the same set of partitions, but the schemes may have different partition methods, different partition keys, and/or different partition bounds.

Abstract: In an approach, a database management system logically partitions a database object (such as a table) across multiple pluggable databases of a container database. When a database server receives a query at an application root, the database server consults a container map which provides a mapping between a set of partitioning criteria and a set of member pluggable databases of the application root. Using the container map, the database server identifies one or more pluggable databases of the set of member pluggable databases of the application root that contain records which potentially have the ability to match the predicates of the query. The database server then limits the execution of the query to the identified pluggable databases, effectively pruning away records contained by the other pluggable databases to increase the efficiency of executing the query.

Abstract: In an approach, memory usage within a database management system is optimized by designating an application root which stores data and metadata for database objects that are common across pluggable databases which support the same application. In addition, the application root can be used to manage access to the pluggable databases by defining common users which are created at the application root, but can be used to access any of the member pluggable databases. Furthermore, different versions of the same application can be supported concurrently by maintaining separate application roots for each version. For instance, when an upgrade is applied to the application root, a clone can be created and the update can be applied to the clone. Then, the member pluggable databases which are to be upgraded can be synchronized to the clone, while leaving other pluggable databases servicing the previous version of the application.

Abstract: Techniques are provided for diverting, to cloned metadata, live access to original metadata of an application container that is being concurrently upgraded. In an embodiment, a database server stores, within an application container of an application, original metadata that defines objects for use by pluggable databases of the application. The database server receives a maintenance request to adjust the original metadata. The database server creates, in response to receiving the maintenance request, a reference container that contains cloned metadata that is a copy of the original metadata. The database server receives, during or after creating the reference container, a read request to read one of the objects. The database server concurrently performs both of: executing the maintenance request upon the original metadata, and executing the read request upon the cloned metadata of the reference container.

Abstract: In an approach, when a pluggable database within a container database is transported to a new container database, the pluggable database is replaced with a proxy pluggable database storing forwarding information for the pluggable database. When a command is received that is to be executed on the proxy pluggable database, the database server handling the command uses the forwarding information stored within the proxy pluggable database to forward the command to a second database receiver responsible for the new container database for execution on the pluggable database. The result of executing the command is then returned to the first database server. Thus, application code which references the pluggable database within the original container database does not have to be rewritten to reference the new location and can remain agnostic as to the actual location of the pluggable database.

Abstract: A query may be rewritten to leverage information stored in a structured XML index. An operator in the query may be analyzed to determine an input source database object for the operator by traversing an operator tree rooted at the operator. The path expressions associated with the operator tree may be fused together to form an effective path expression for the operator. If the effective path expression directly matches a path expression derived from the index, the query may be rewritten using references to the index. Operators in a query that have effective paths that refer to data in the same index table may be grouped together. A single subquery may be written for a group of operators. Also, a structured XML index may be used as an implied schema for indexed XML data. This implied schema may be used to optimize queries that refer to the indexed XML data.

Abstract: A database session in an active standby server on which an active standby database resides receives a DML statement. The session is suspended while the statement is redirected over a database link to a primary database on which the statement is executed. Information associated with execution of the statement is communicated to the session in the active standby server. Redo records describing changes to the contents of the primary database are applied to the active standby database and control is returned to the session. Prior to commitment of a transaction including the statement, a query directed to data to which the statement was directed is received at the active standby server from a client and executed on the active standby database absent use of a database link based on whether information associated with a database session associated with the client matches the information associated with execution of the statement.

Abstract: Techniques are provided for diverting, to cloned metadata, live access to original metadata of an application container that is being concurrently upgraded. In an embodiment, a database server stores, within an application container of an application, original metadata that defines objects for use by pluggable databases of the application. The database server receives a maintenance request to adjust the original metadata. The database server creates, in response to receiving the maintenance request, a reference container that contains cloned metadata that is a copy of the original metadata. The database server receives, during or after creating the reference container, a read request to read one of the objects. The database server concurrently performs both of: executing the maintenance request upon the original metadata, and executing the read request upon the cloned metadata of the reference container.

Abstract: A method and apparatus for automatically analyzing and providing feedback regarding the optimizability of a relational database query. A query developer's primary goal is to ensure that queries and DML operations are rewritten for the most efficient execution. Rewrite diagnosability captures metadata for each attempted query optimization including success or failure and the reasons for failure. The metadata is stored in association with the operators that were not removed through rewriting. Once all optimizations have been attempted and rewriting is complete, the metadata is selectively displayed based on the cost to perform the associated operation. The context of performing the operation may affect the cost. The cost may be based at least on the type of operation and where within the query tree the operation is located. A query developer may configure the database system not to execute the resulting query plan based on one or more criteria.

Abstract: In an approach, memory usage within a database management system is optimized by designating an application root which stores data and metadata for database objects that are common across pluggable databases which support the same application. In addition, the application root can be used to manage access to the pluggable databases by defining common users which are created at the application root, but can be used to access any of the member pluggable databases. Furthermore, different versions of the same application can be supported concurrently by maintaining separate application roots for each version. For instance, when an upgrade is applied to the application root, a clone can be created and the update can be applied to the clone. Then, the member pluggable databases which are to be upgraded can be synchronized to the clone, while leaving other pluggable databases servicing the previous version of the application.

Abstract: In an approach, when a pluggable database within a container database is transported to a new container database, the pluggable database is replaced with a proxy pluggable database storing forwarding information for the pluggable database. When a command is received that is to be executed on the proxy pluggable database, the database server handling the command uses the forwarding information stored within the proxy pluggable database to forward the command to a second database receiver responsible for the new container database for execution on the pluggable database. The result of executing the command is then returned to the first database server. Thus, application code which references the pluggable database within the original container database does not have to be rewritten to reference the new location and can remain agnostic as to the actual location of the pluggable database.