A Semantic Approach to Enforce Correctness of Data Distribution Schemes

Improving Data Quality Control in the Xplain-DBMS

“…The concept of "element" refers to itself via "element its preceding_element". Similar recursive structures are also an essential part of meta models for data distribution and parallel input/output in database management systems (Bakker, 1994(Bakker, , 1998.…”

An extended meta model for conditional fragmentation

“…In the context of the Xplain DBMS (Ter Bekke, 1980Bekke, , 1992Bekke, , 1994Bekke, , 1995Bekke, , 1996Bekke, , 1997aBekke, , 1997bBekke, , 1997cRolland, 1998), the enforcement of correctness of fragmentation schemes could be based on a meta model and additional rules (Bakker, 1994). Only the following kinds of fragmentation for composite types (types having attributes) were allowed:…”

“…SQL even allows join operations that ignore the structure (semantics) of a data model (Ter Bekke, 1992, 1997bBakker, 1994). Although it is possible to specify fragmentation correctly by applying a (somewhat extended) data manipulation language, it remains possible to specify syntactically correct but semantically incorrect fragments and to forget some fragments.…”

“…Both primary and derived fragmentation could be specified through conditions using inheritance paths (links) built through a sequence of one or more attributes (Bakker, 1994). We did not propose any (analytical) method for the design of fragmentation, the objective only was to design a generic declarative solution for the correctness of data distribution schemes.…”

“…The concepts of 'path attribute', 'instance' and 'group' were in~oduced previously (Bakker, 1992(Bakker, , 1994. Their definition and the related abstraction hierarchy are shown in figure 3.…”