摘要:
Systems, methods, and other embodiments associated with query processing in light of an ontology are described. One example system includes a data store that stores both data concerning entities and data concerning relationships between the entities. The data may be logically arranged as an ontology and thus may include nodes and labeled relationships. The system may also include a query processing logic that can control a search logic to search for documents relevant to a query. Control exercised by the query processing logic may depend, at least in part, on data in the ontology.
摘要:
Constraints that restrict how corresponding identifiable groups of files are stored in a database, are enforced on corresponding file data. In response to a query on any data from an identifiable group of files, the effect of the constraint on how the corresponding data is stored is determined. The original query is rewritten, based on the effect of the constraint, so that the rewritten query is directed to a particular subset of the data stored in the database. Consequently, the search space is restricted to an identifiable subset of the database and execution of the rewritten query is more efficient than execution of the original query.
摘要:
A method and system are provided for allowing users to register XML schemas in a database system. The database system determines, based on a registered XML schema, how to store within the database system XML documents that conform to the XML schema. This determination involves mapping constructs defined in the XML schema to constructs supported by the database system. Such constructs may include datatypes, hierarchical relationship between elements, constraints, inheritances, etc. Once the mapping has been determined, it is stored and used by the database system to determine how to store subsequently received XML documents that conform to the registered XML schema.
摘要:
Techniques are provided for processing a query, including receiving the query, where the query specifies certain operations to be performed, including (a) a first set of one or more operations that are to be performed on a markup language data source and (b) a second set of one or more operations that are to be performed on a second data source. Then it is determined that a first server that manages the markup language data source is capable of performing the first set of operations. A request is sent to the first server to perform the first set of operations. A response is received, where the response contains results of performing the first set of operations on the markup language data source. Finally, results are generated for the query based at least in part on the results of performing the first set of operations.
摘要:
Object-relational database systems process XML values in a way that preserves node identities of nodes in the XML values and perform node-id based operations more efficiently or even in circumstances where such operations were not performed. An object-relational database system represents an XML value as a serialized stream of bytes, herein referred to as a serialized image. A serialized image may represent an XML value of the XMLType that is stored and/or generated by an object-relational database system. The serialized image contains one or more node identifiers that identify nodes within the XML value. The serialized image may also contain a pointer to an in-memory representation of the XML value, allowing the in-memory representation to be accessed via the pointer without having re-create the in-memory representation.
摘要:
Techniques are provided for processing a query including receiving the query, where the query specifies certain operations; determining that the query includes a first portion in a first query language and a second portion in a second query language; generating a first in-memory representation for the first portion; generating a second in-memory representation for the second portion; generating a third in-memory representation of the query based on the first in-memory representation and the second in-memory representation; and performing the certain operations based on the third in-memory representation.
摘要:
Techniques are provided for mapping XML data and metadata from data in relational databases. According to certain embodiments of the invention, a mechanism is provided to allow the user to use a database query to retrieve data form a relational database in the form of XML documents by canonically mapping object relational data to XML data and canonically mapping object relational schemas to XML-Schemas. The mechanism causes the generation of XML-schema information for the XML documents.
摘要:
A mechanism is provided for accessing XML data in a database system using a combination of a XML Table Index table and a XML Path Index table. By using a combination of a XML Table Index and a XML Path Index, both selection access and navigational access involved in a query can be optimized. For example, the XML Table Index gives the database system an ability to readily evaluate the predicate expression, thereby improving the selection access. Moreover, in some embodiments, the selection access can be further improved by using secondary indexes on columns contained in the XML Table Index table. In a complementary manner, the XML Path Index table gives the database system an ability to navigate to a specific location given a path expression, thereby improving the navigational access. Thus, by combining both tables, both selection and navigational accesses are improved.
摘要:
Aspects of the subject matter described herein relate migrating message for a messaging service. In aspects, a determination is made that messages need to be migrated based on a threshold being crossed. In response, an agent is instructed to migrate data associated with the messages to another location. The agent uses various factors to determine one or more queues to migrate. While a queue is being migrated, during a first portion of the migration, messages may be added to and removed from the queue as senders send new messages and receivers consume messages. During a second portion of the migration, the queue is frozen to disallow the queue to be used for receiving new messages and delivering queued messages. The migration may be orchestrated to attempt to achieve certain goals.
摘要:
Techniques are described herein for storing instances of data among nodes of a distributed store based on hierarchical scale unit values. Hierarchical scale unit values are assigned to the respective nodes of the distributed store. A first instance (e.g., a primary instance) of a data module is stored in a first node having a first hierarchical scale unit value. A primary instance of the data module with respect to a data operation is an instance of the data module at which the data operation with respect to the data module is initiated or initially directed. A second instance (e.g., a primary or secondary instance) of the data module is stored in a second node having a second hierarchical scale unit value based on a magnitude of a difference between the first hierarchical scale unit value and the second hierarchical scale unit value. A secondary instance is essentially a “back-up” instance.