I have a ABAP CDS view in an ERP backend which uses a union with two selects.
Without the union one select takes about 4 seconds to load the data, the other select about 5 seconds.
With the union the loading takes about 1 Minute. I also tried using "union all", but performance did'nt change.
Does anyone has an idea how I could optimize the performance?
Why does it take so long, when the single selects just take some seconds to load?