Diagnosis
The delta index was created for the selected index. This means thatduring the next rollup of data or change run in which new data iswritten to this index, there will be a merge of the delta index and themain index. Then the new data is only written to the main index.
If the MERGE" takes more time because the index is very large, theruntime of the next process can be longer. From then on, a "MERGE" is nolonger required.