The global food discounter "ALJENE" introduces a data warehouse (DWH). So far, there are no uniform reporting structures in the group.

a) The IT manager wants to introduce a "central DWH architecture", the sales manager "independent data marts". As an external consultant, you have been brought in to make a decision. Choose one of the variants and justify your decision. In doing so, go into the properties of both variants.

b) After the introduction of the DWH, OLAP analyzes can now be carried out. ALJENE opens all branches worldwide for 14 hours a day (8 a.m. to 10 p.m. local time). However, the OLAP analysis shows that sales are apparently made for 18 hours (or even longer) in individual branches. The IT manager can rule out a technical error. Give a reason as to how this analysis result can come about and what a possible cause is.