摘要:
Systems, methods, and other embodiments associated with query pruning via query rewrite are described. One example method includes receiving a query on a partitioned table that will result in a first query plan that includes accessing a local domain index on each partition in the database. The query is rewritten to generate a second query that will result in a second query plan that includes accessing a global domain index instead of the local domain index on each partition in the database.
摘要:
Systems, methods, and other embodiments associated with query pruning via query rewrite are described. One example method includes receiving a query on a partitioned table that will result in a first query plan that includes accessing a local domain index on each partition in the database. The query is rewritten to generate a second query that will result in a second query plan that includes accessing a global domain index instead of the local domain index on each partition in the database.
摘要:
Techniques are described for generating histograms for a multidimensional space. In the presence of large spatial objects, fuzzy splitting techniques are utilized to recursively divide the multidimensional space into partitions, where a single spatial object may belong to multiple partitions. Large spatial objects are essentially broken down into smaller objects that may allow for more efficient partitioning of the multidimensional space. A count of spatial objects in each partition yields a spatial histogram. A spatial object that belongs to multiple partitions may have a weighted count for each of the multiple partitions, based on the extent to which the spatial object overlaps with each partition. Thus, an object that is split among a handful of partitions will only contribute a fraction of a count to each partition. Small partitions having relatively few objects are avoided by refusing to subdivide a partition whose members drop below a threshold number.
摘要:
Techniques are described for generating histograms for a multidimensional space. In the presence of large spatial objects, fuzzy splitting techniques are utilized to recursively divide the multidimensional space into partitions, where a single spatial object may belong to multiple partitions. Large spatial objects are essentially broken down into smaller objects that may allow for more efficient partitioning of the multidimensional space. A count of spatial objects in each partition yields a spatial histogram. A spatial object that belongs to multiple partitions may have a weighted count for each of the multiple partitions, based on the extent to which the spatial object overlaps with each partition. Thus, an object that is split among a handful of partitions will only contribute a fraction of a count to each partition. Small partitions having relatively few objects are avoided by refusing to subdivide a partition whose members drop below a threshold number.
摘要:
One example method of spatial query processing using query window indexes includes receiving a spatial query on spatial data that has an associated spatial data index. The spatial query specifies a query window. A query window index structure is constructed that describes a geometry of the query window. The query window index structure is compared to the spatial data index and, when necessary, to the spatial data to determine a spatial relationship between the query window and the spatial data.
摘要:
A database management system that has bitmap values in which set bits in a representation of a bitstring specify a set of objects whose definitions are built into the database management system. The database management system further includes user-accessible operations on the bitmap values. The bitmap values are represented by means of a mapping specifier that specifies a range of the set of objects and a representation of a string of bits that has been mapped onto the set of object specified by the range specifier. Objects containing bitmap values may be indexed by means of an index tree that includes summary bitmap values.
摘要:
In one embodiment, a database server registers one or more functions included in a user-defined index that includes one or more auxiliary properties. The one or more functions are operable to generate index entries of the user-defined index for the one or more auxiliary properties. The one or more auxiliary properties are different than, and in addition to, a primary property of the user-defined index that provides for evaluating a query operator. The database server receives a first statement that defines the user-defined index, where the first statement includes one or more parameters that define the one or more auxiliary properties. The database server invokes the one or more functions in response to the first statement, where the one or more functions when invoked generate and store the index entries of the user-defined index according to the one or more parameters that define the one or more auxiliary properties.
摘要:
Systems, methodologies, media, and other embodiments associated with supporting queries with soft time constraints are described. One exemplary system embodiment includes logic for accepting a query having a soft time constraint. The example system may also include logic for rewriting the query having the soft time constraint into a query having a row limitation or a sample percentage limitation. In one example, the row limitation or sample percentage limitation are computed by repetitively comparing an estimated query execution time to the soft time constraint.
摘要:
A database management system that has bitmap values in which set bits in a representation of a bitstring specify a set of objects whose definitions are built into the database management system. The database management system further includes user-accessible operations on the bitmap values. The bitmap values are represented by means of a mapping specifier that specifies a range of the set of objects and a representation of a string of bits that has been mapped onto the set of object specified by the range specifier. The representation of the string of bits may be compressed. Bitmap operations on the values may alter the range specifier, the size of the string of bits, or individual bits in the string of bits. The objects represented by the bitmap values may be objects in the database management system or objects external thereto. An example of bitmap values of the first kind are bitmap values representing sets of rowids. rowid bitmap values may be used to make a user-defined index of attribute values for any set of objects contained in fields in the database management system. An example of bitmap values of the second kind are bitmap values representing sets of electronic product codes. ePC bitmap values may be used in any application where a compact representation of a set of ePC codes is desired.
摘要:
Domain indexes (indexes created and maintained by user-defined indexing schemes) are managed on partitioned database objects that store data using a system-managed approach. Partition maintenance operations performed on the partitioned database objects cause corresponding partition maintenance operations to be performed on the domain indexes. Partition maintenance operations are performed on both the database objects and the indexes by a system-supplied partition manager. Changes in the partition maintenance operations or partitioning methods supplied by the database management system do not affect user-supplied code which is provided by the user-defined indexing scheme. User-supplied code is therefore partition operation-unaware.