Hi Somine,
We have 5 secondary indexes , now 6. 4 of them were created to speed up performance few years ago but in my opinion they are not efficient when the dynamic where clause contains more fields than the index and order by which is non-existent in the sec. index. Especially the data has grown so much in size after these years. It is clear now that the DB took its time to search for the matches because of the partial index.
Now with the new sec. index (containing exactly the fields as the where clause in the exact same order as well as the order by field) and the slimmed down where clause, it cuts down to less than 1 sec! And yes, its hitting 4 key columns!
Now I get it why the saying 'the system is slow' since I joined a year ago. Ticket on performance was finally raised before Christmas last year. With indexes like these...there is a limit to how fast it can go.
Thank you all for your input!
Cheers!