We had a big problem with our production system today. The customer determined we had not been transferring some files for a couple week. And those are some of our most crucial files. We had a big TO DO list to work this problem. I signed up to analyze the damage that was done to the business.At first I ran some queries on a pretty large set of data. Our server is a massive one with tons of CPUs and memory. However these queries took a long time. I published the results. The managers wanted more details. They were looking for a way to spin the data to do the least amount of damage to our image. I told them this would take a long time. So I went home and brought my computer with me.
Here was the surprising thing. When I ran the SQL and divided up the result with a GROUP BY function, the queries seemed to run faster. Perhaps the database was able to split the pieces of the query amongst the CPUs better. Or maybe my prior query results were cached, and the database could take advantage of the result set. Whatever the reason, I was happy that my homework was not taking too long. I was able to knock out the tasks and move on to the next emergency. I even got time to eat dinner and watch a movie this evening. Thanks Oracle10g.
