Is it useful to create a multiple index on the fact table using the fields of different dimensions?
If several restrictions on different dimensions are relatively unselective in queries, a multiple index on the corresponding dimension fields can improve the performance. A multiple index should generally be defined on two or a maximum of three dimension fields. The data in the fact table is sorted (by the SYSKEY) and therefore stored according to the sequence of inserted records. Since the data is loaded on time into the BW system, records with time characteristics are close to each other, which means that (when data is read using a time characteristic) you can expect a lot of hits on a data page – this in turn means that fewer pages have to be loaded into the data cache. The MaxDB optimizer does not have this information. It can therefore be more beneficial to select data using time characteristics, even if other characteristics are more selective. You can optimize access by creating a suitable multiple index on the fact table that contains a time characteristic and the selective cha
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