Abstract: A catalog of one or more metadata objects associated with metadata is stored in a persistent manner. The data objects are stored at least in part on a user node included in a data management system. A request associated with accessing a metadata object included in the persistent catalog is received. In response to receiving the request, access to the requested metadata object is provided.

Abstract: Database system comprising nodes configured in a tree structure is disclosed. The system includes a shared metadata store on the root node. Child nodes may request metadata from their ancestors. Parents will forward the request upward until the metadata is found or the root node is reached.

Abstract: A process for upgrading a mirrored shared-nothing database system comprises a sequence of short well-defined idempotent steps, and at least one non-idempotent step involving transforming a master catalog. The upgrade process is managed and controlled by a state machine that has a persistent memory running on the master node. In the event of a failure or crash during an idempotent step, the process stops the database in the current state and repeats the step. If a failure or crash occurs during a non-idempotent step, the upgrade process is rolled back to the beginning and repeated.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A computer readable storage medium includes executable instructions to evaluate an expanded shared-nothing data store configuration. A data redistribution schedule table with specified parameters is formed. Data is redistributed within the expanded shared-nothing data store in accordance with the data redistribution schedule table.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A computer readable storage medium includes executable instructions to evaluate an expanded shared-nothing data store configuration. A data redistribution schedule table with specified parameters is formed. Data is redistributed within the expanded shared-nothing data store in accordance with the data redistribution schedule table.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A process for upgrading a mirrored shared-nothing database system comprises a sequence of short well-defined idempotent steps, and at least one non-idempotent step involving transforming a master catalog. The upgrade process is managed and controlled by a state machine that has a persistent memory running on the master node. In the event of a failure or crash during an idempotent step, the process stops the database in the current state and repeats the step. If a failure or crash occurs during a non-idempotent step, the upgrade process is rolled back to the beginning and repeated.

Abstract: A script is run on a database to transform the metadata and produce an upgraded database. A new database corresponding to the upgraded database is initialized, and the metadata in the new database catalog is verified by comparing it to the upgraded database metadata. A fast verification is performed on a partial upgrade by dumping the catalogs of master nodes and comparing the results, and a thorough verification is performed on a full upgrade by querying and comparing both master node catalogs and segment node catalogs.

Abstract: A computer readable storage medium includes executable instructions to define a map-reduce document that coordinates processing of data in a distributed database. The map-reduce document complies with a map-reduce specification that integrates map-reduce functions with queries in a query language. The operations specified by the map-reduce document are executed in the distributed database.

Abstract: A computer readable storage medium includes executable instructions to evaluate an expanded shared-nothing data store configuration. A data redistribution schedule table with specified parameters is formed. Data is redistributed within the expanded shared-nothing data store in accordance with the data redistribution schedule table.

Abstract: A computer readable storage medium includes executable instructions to store load data in new rows of an append only table within a data warehouse, without updating or deleting existing rows in the append only table. The new rows are added in a database transaction that guarantees that the distributed reads and writes of all transactions are processed reliably and that the transactions obey snapshot isolation rules. Data changes associated with the load data are maintained in a separate update table. Data from the append only table is merged with data changes from the update table to supply read data.

Abstract: A computer readable storage medium includes executable instructions to define a map-reduce document that coordinates processing of data in a distributed database. The map-reduce document complies with a map-reduce specification that integrates map-reduce functions with queries in a query language. The operations specified by the map-reduce document are executed in the distributed database.

Abstract: A method and apparatus for processing a query combines the use of different index types to minimize the rows of data that need to be retrieved from a table. A first index is accessed based on a query to produce a first result having a first format, for example a bitmap index outputting a bitmap. A second index, for example a B-tree index, is also accessed based on the query to produce a second result having a second format, for example a sequence of rowids. The first result is converted to a converted result having the second format, and the converted result and the second result are combined to obtain an end result. The end result can then be used to locate data that satisfies the query while minimizing the rows of data that need to be retrieved from a table during the query processing.

Abstract: Sort plus operations such as "group by" and "distinct" generally require sorting of the retrieved data before performing the sort plus operation. A method and apparatus is disclosed for executing a query specifying a sort plus operation without performing the sorting operation. To perform the sort plus operation, it is determined whether a sorted source exists that can be used to obtain the data specified in the query. If the sorted source does exist, it is then used to perform the sort plus operation.

Abstract: A method and apparatus for processing a query combines the use of different index types to minimize the rows of data that need to be retrieved from a table. A first index is accessed based on a query to produce a first result having a first format, for example a bitmap index outputting a bitmap. A second index, for example a B-tree index, is also accessed based on the query to produce a second result having a second format, for example a sequence of rowids. The first result is converted to a converted result having the second format, and the converted result and the second result are combined to obtain an end result. The end result can then be used to locate data that satisfies the query while minimizing the rows of data that need to be retrieved from a table during the query processing.

Abstract: Sort plus operations such as "group by" and "distinct" generally require sorting of the retrieved data before performing the sort plus operation. A method and apparatus is disclosed for executing a query specifying a sort plus operation without performing the sorting operation. A cost-based optimizer determines at least one execution path where the data is retrieved from a sorted source and the data is processed to satisfy the query without sorting. Execution costs are determined for the respective execution paths, and the execution path having the lowest overall execution cost is selected to process the query.