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Control Data Base Manager

IP.com Disclosure Number: IPCOM000080480D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 5 page(s) / 223K

Publishing Venue

IBM

Related People

Conroy, ED: AUTHOR

Abstract

A data base may be used for controlling a collection of items, e.g., parts. The data base essentially stores values of attributes that are associated with the items. A storage structure in such a data base is logically dense, i.e., the set of attributes is common to all items, and each item has values for all attributes. Retrieval of an item from the data base normally involves obtaining the values of specified attributes for selected data objects (which correspond to the controlled items). Selection criteria (S(c)) involve values of other specified attributes. This may involve a simple explicit criterion as represented by: S(c) = A(1)(A(2) = V(2)). which requests the value of attribute A in all objects meeting the criterion that attribute A(2) has a value V(2).

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Control Data Base Manager

A data base may be used for controlling a collection of items, e.g., parts. The data base essentially stores values of attributes that are associated with the items. A storage structure in such a data base is logically dense, i.e., the set of attributes is common to all items, and each item has values for all attributes. Retrieval of an item from the data base normally involves obtaining the values of specified attributes for selected data objects (which correspond to the controlled items). Selection criteria (S(c)) involve values of other specified attributes. This may involve a simple explicit criterion as represented by: S(c) = A(1)(A(2) = V(2)). which requests the value of attribute A in all objects meeting the criterion that attribute A(2) has a value V(2). This may also involve compound recursively-defined levels of criteria as represented by: S(c) = -A(1)(A(2) = A(3)((A(4) = V(4)). (A(5) = V(5)))) which requests the value, V(1), of attribute A(1) in any object in which attribute A(2) has a value equal to the value of attribute A(3) in any object in which attribute A(4) has a value V(4) and attribute A(5) has a value V(5).

In many cases, the set of possible values for an attribute or attribute group is smaller than the number of attribute/object combinations to which the set applies. In such cases, and especially if the values can be relatively long EBCDIC strings, space can be saved by storing a value code in the objects. The actual value is stored only once in a Value Table defining the value set, and the code indicates its relative position. In addition, since the codes have a constant length this saves space within the objects.

Each actual value is linked to a chain of Value Usage Tables. Each such table represents an attribute which has that value in at least one object, and lists all such objects. This permits rapid resolution of compound queries, since object selection can be done by simply editing these tables without any need for actually reading the objects.

Fig. 1 shows the table structure associated with such a data base. For simplicity, the hash dictionaries assume no conflicts and show no conflict lists. Figs. 2 through 4 are flow charts of the three basic processes involv...