Back in 2017 I wrote about how I had to disable the result cache after upgrading a database to 188.8.131.52. This week I found one of our top queries and it looked like removing the result cache hints made it run 10 times faster. But this did not make sense because I disabled the result cache. Then I examined the hints closer. They looked like this:
/*+ RESULT CACHE */
There should be an underscore between the two words. I look up hints in the manuals and found that CACHE is a real hint. So, I tried the query with these three additional combinations:
/*+ RESULT */
/*+ CACHE */
/*+ RESULT_CACHE */
It ran slow with the original hint and with just the CACHE hint but none of the others. So, the moral of the story is to check your hints carefully because they may not be what you think they are.