摘要:
A method and system for efficient snapshot querying include: providing a first version value for each data in a history table, where the first version value indicates a beginning of a period in which the data is valid; providing at least a second version value for each data in the history table, where the second version value indicates an end of the period in which the data is valid; receiving a request for a version of a database; and retrieving the data with the first version value less than or equal to the requested version and the second version value greater than or equal to the requested version. By maintaining a history table with redundant version information, the method and system are able to provide efficient snapshot querying while also avoiding the overhead burden of conventional approaches. No aggregates, joins, or sub-queries are required to retrieve a snapshot.
摘要:
A system for synchronizing data on a first device with data at a second device, includes: determining a pre-image of the data on the first device according to a filter after a previous synchronization with the data at the second device; determining a current image of the data at the second device according to the filter; determining a delta of the current image, where the delta comprises data that exists in the current image and has changed since the previous synchronization; instructing the first device to delete data that exists in the pre-image but not in the current image; and instructing the first device to UPSERT a union of the data that exists in the delta and the data that exists in the current image but not the pre-image. This is efficient in time and bandwidth resources while also providing consistent data integrity.
摘要:
A technique is provided for generating one or more XML documents from a single SQL query. Data stored on a data storage device that is connected to a computer is transformed. A query is received that selects data stored in a relational database management system on the data storage device, wherein a data access definition defines: (1) a collection of one or more tables in the relational database management system for storing attributes from an XML document, (2) how data stored in the tables maps to the XML document, (3) a query for mapping the data stored in the tables to the XML document, and (4) a table that will contain the XML document after the XML document is generated. Then, one or more XML documents are generated from the selected data using the data access definition.
摘要:
A technique is provided for creating metadata for fast search of XML documents stored as column data. Data is stored in a data store connected to a computer. A main table is created in a relational database management system, wherein the main table has a column for storing an extensible markup language (XML) document in a native XML format One or more side tables are created in the relational database management system, wherein each side table has one or more columns that store one or more attributes extracted from die XML document for fast searching of the XML document. Thereafter, the side tables are used to locate data in the main table.
摘要:
A technique is provided to store fragmented XML data into a relational database by decomposing XML documents with application specific mappings. Data stored on a data store that is connected to a computer is transformed. Initially, an XML document containing XML data is received. A document access definition that identifies one or more relational tables and columns is received. The XML data is mapped from the application DTD to the relational tables and columns using the document access definition by generating a first document object model tree using the XML document, generating a second document object model tree using the document access definition, and mapping the data from the first document object model tree into columns in one or more relational rabies using the second document object model tree.
摘要:
A system for efficient snapshot querying include: providing a first version value for each data in a history table, where the first version value indicates a beginning of a period in which the data is valid; providing at least a second version value for each data in the history table, where the second version value indicates an end of the period in which the data is valid; receiving a request for a version of a database; and retrieving the data with the first version value less than or equal to the requested version and the second version value greater than or equal to the requested version. By maintaining a history table with redundant version information, the system is able to provide efficient snapshot querying while also avoiding the overhead burden of conventional approaches. No aggregates, joins, or sub-queries are required to retrieve a snapshot.
摘要:
A system for synchronizing data on a first device with data at a second device, includes: determining a pre-image of the data on the first device according to a filter after a previous synchronization with the data at the second device; determining a current image of the data at the second device according to the filter; determining a delta of the current image, where the delta comprises data that exists in the current image and has changed since the previous synchronization; instructing the first device to delete data that exists in the pre-image but not in the current image; and instructing the first device to UPSERT a union of the data that exists in the delta and the data that exists in the current image but not the pre-image. This is efficient in time and bandwidth resources while also providing consistent data integrity.
摘要:
A system for efficient snapshot querying include: providing a first version value for each data in a history table, where the first version value indicates a beginning of a period in which the data is valid; providing at least a second version value for each data in the history table, where the second version value indicates an end of the period in which the data is valid; receiving a request for a version of a database; and retrieving the data with the first version value less than or equal to the requested version and the second version value greater than or equal to the requested version. By maintaining a history table with redundant version information, the system is able to provide efficient snapshot querying while also avoiding the overhead burden of conventional approaches. No aggregates, joins, or sub-queries are required to retrieve a snapshot.
摘要:
A method for synchronizing data on a first device with data at a second device, includes: determining a pre-image of the data on the first device according to a filter after a previous synchronization with the data at the second device; determining a current image of the data at the second device according to the filter; determining a delta of the current image, where the delta comprises data that exists in the current image and has changed since the previous synchronization; instructing the first device to delete data that exists in the pre-image but not in the current image; and instructing the first device to UPSERT a union of the data that exists in the delta and the data that exists in the current image but not the pre-image. This is efficient in time and bandwidth resources while also providing consistent data integrity.
摘要:
A technique is provided for generating one or more XML documents from a relational database using the XPath data model. Data stored on a data storage device that is connected to a computer is transformed. Initially, a document object model tee is generated using a document access definition, which defines the mapping between an XML tree structure and relational tables. The document object model tree is traversed to obtain information to retrieve relational data. The relational data is mapped to one or more XML documents.