Comparison
Conformed dimensionvsData mart
Conformed dimension
marketing and finance both group by the same customer dimension, so their two reports can finally be put side by side.
A dimension shared identically across several fact tables, so measures from different processes can be compared along it. It is the mechanism by which a warehouse becomes more than a pile of marts: without conformance, every team's 'region' is subtly different and cross-process comparison is guesswork. Building one is mostly a negotiation rather than an engineering task, which is why it is the piece that is usually skipped and later regretted.
Full entry →Data mart
the finance team has its own set of tables, shaped for their questions, built from the shared ones.
A subset of the warehouse modelled for one team or one subject area. Built on conformed dimensions it is a useful presentation layer; built independently from source it becomes a second warehouse with its own definition of revenue, which is how organisations end up with four numbers for one metric. The distinction between those two outcomes is entirely whether the shared dimensions came first.
Full entry →