In the maintenance of a stored relational database, signals representing record occurrences related to a record occurrence of a starting relation are retrieved. Stored relationship attribute signals, including specification of a common relationship field, are used to generate a generic cursor defined against the destination relation record occurence is selected, values of the specified relation; the generic cursor is stored, and when a starting field are copied from it to the generic cursor to form a completed cursor. Destination relation record occurrence signals defined by the completed cursor are accessed and stored. Retrieval can be carried out interactively, allowing an operator to select from a display the starting relation record occurrence and the operation of retrieving the related occurrences, and to view representations of the stored destination record occurrences.
This is a continuation of co-pending application Ser. No. 07/040,705 filed on 04/17,87, now abandoned, which is a continuation of Ser. No. 06/691,036 filed on 01/11/85, now abandoned.
A data model for an information repository (10) models data as objects (12), the relationships (14) or interdependencies between the data, their physical storage or access information (18) and rules or methods of accessing the data (16).
An index set for a databse is specified by analyzing a sample (718) of SQL statements applied to the database (701). Indexes (707) are identified that could assist in the execution of the analyzed statements and levels of improved operation are evaluated for each of said indexes. The evaluated levels are then processed (708) to specify an index set for inclusion on the database. The database may not include sufficient storage (702) for all of the specified indexes to be included, therefore the available storage space is allocated and indexes are selected on a prioritized basis.
A method for more accurately estimating the time required to process a data base query using a selected index. A selected number of the most frequently occurring index key values (38) are collected during an index sequential scan. These most frequency occurring values are stored as percentage frequencies of occurrence in the data base system's catalog (42). Estimated access and processing times (NPAR, NPAS, NCPU) for a given query are calculated based on the stored frequencies where possible. Where the query's search criteria specify values other than the stored most frequently occurring values, those values are assumed to be uniformly distributed.
A slip input apparatus which when retrieving an index record with abbreviation data input, permits an operator to easily and arbitrarily set which field of the index record is to be used to retrieve an index file, which field data in the retrieved index record is to be output, and which field data in the retrieved index record is to be fetched as input data. Accordingly, irrespective of the type of data entered in abbreviation, a user is allowable to output arbitrary field data or fetch arbitrary field data from a memory as input data.
A data model for an information repository (10) models data as objects (12), the relationships (14) or interdependencies between the data, their physical storage or access information (18) and rules or methods of accessing the data (16).
