Abstract: A database system, method, and computer program product of handling purchases of products is presented, in which the database system comprises a relational database storing relational data for a plurality of products, a key-value database storing a plurality of first files and a plurality of second files, an interface module connecting the relational database with the key-value database, and a shopping engine to communicate with the key-value database. The interface module converts relational data stored in the relational database into first files and second files. The shopping engine queries the key-value database to retrieve available products in response to an availability request.

Abstract: A computer-implemented method comprising: receiving a user-generated request comprising functional data; retrieving a list of data items and a set of dependency rules, each data item being assigned an undefined binary validity value; generating a directed graph by organizing the data items in accordance with the retrieved dependency rules; applying a filtration process to solve the directed graph comprising: calculating the validity value; propagating the validity values through the graph; and filtering the directed graph by keeping only nodes having a validity value of one; calculating, for each filtered data item, a price; and generating a list of available data items with their price. The node suppression decreases the number of data items for which a price has to be calculated, thereby saving resources and/or decreasing the time needed to resolve the user request.