Certify Your Experience
During my first day in the BSF in Riyadh, I had to deal with database problem that needs SQL tuning. I thought at the beginning it needs some simple tuning like EXISTS and query hints, but preferred to see how a certified DBA will deal with that query.
Originally the query was taking round 1 minutes , but the performance issue was reported the query was taking around 9 minutes to return. When the DBA started to deal with it, he identified one or two things that could cause that issue, one of them was the extensive use of the CASE statement since it force the ORACLE DBMS to perform some processing on the retrieved data after the query return the Dataset, and this appeared clearly when we saw the query plan and the number of temp views created by the DBMS to process the CASE statements.
Meanwhile I was working to solve these issues, he asked me to try to run the original query again, amazingly the query was taking 5 seconds to end. That time he applied some database procedure that tunes the tables involved into this query to run faster, this procedure called Histogram.
The thing that came to my mind is that I'm experience in many software fields either technical or analytical, but I did not get any certifications to support this experience and fill the gaps of knowledge.
