摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The history table's rows are copies of rows of the history-enabled table that have changed and include start time and end time fields whose values indicate a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table. The temporal queries are speeded up by period of time indexes in which the leaves are grouped based on time period size, identifiers are assigned to the groups, and the keys of the index include the group identifiers.
摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The start time field's value in a row of the history-enabled table indicates when the contents of the row last changed. The rows of the history table are copies of rows of the history-enabled table that have been deleted or updated. The rows include end time fields whose values indicate when the row was updated or deleted. A history table's row thus indicates a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table.
摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The start time field's value in a row of the history-enabled table indicates when the contents of the row last changed. The rows of the history table are copies of rows of the history-enabled table that have been deleted or updated. The rows include end time fields whose values indicate when the row was updated or deleted. A history table's row thus indicates a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table.
摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The start time field's value in a row of the history-enabled table indicates when the contents of the row last changed. The rows of the history table are copies of rows of the history-enabled table that have been deleted or updated. The rows include end time fields whose values indicate when the row was updated or deleted. A history table's row thus indicates a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table.
摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The history table's rows are copies of rows of the history-enabled table that have changed and include start time and end time fields whose values indicate a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table. The temporal queries are speeded up by period of time indexes in which the leaves are grouped based on time period size, identifiers are assigned to the groups, and the keys of the index include the group identifiers.
摘要:
Techniques for history enabling a table in a database system so that past versions of rows of the history-enabled table are available for temporal querying. The table is history enabled by adding a start time column to the table and creating a history table for the history-enabled table. The start time field's value in a row of the history-enabled table indicates when the contents of the row last changed. The rows of the history table are copies of rows of the history-enabled table that have been deleted or updated. The rows include end time fields whose values indicate when the row was updated or deleted. A history table's row thus indicates a period in which the history table's row was in the history-enabled table. Temporal queries are performed on a view which is the union of the history-enabled table and the history table.
摘要:
A system to implement query-level access by a database engine to an external distributed file system by identifying a results file location of one or more results files on the external distributed file system, and storing the results file locations in external table files on the database engine for subsequent use during retrieval of data from the results files. The database engine serves to process queries where the query specifies the external table (which in turn references locations of the results files). Execution of the query streams data from the external distributed file system into the database engine. The data from the external distributed file system is not stored in the external table files on the database engine; rather, the external table files specify a location of code or operational directives which, when executed, streams results from the external distributed file system to at least one parallel query engine.
摘要:
Interval-based adjustments to data are applied by a relational database engine. The engine stores raw, unadjusted data values in a separate table from adjustment values. The adjustment values are dynamically updated in response to a new adjustment interval. The adjustments are applied to the raw data during retrieval from the database. This results in an efficient and transparent adjustment to data.