This post is not so much a serious investigation, rather, a few curious observations, followed by some general musings prompted by them.
So… When you see a SQL execution plan and runtime statistics like below, what thoughts come to mind?
It has been (unforgivably) long since my last blog post so let me try and rehabilitate myself by posting a couple of recent interesting investigations. I’ll start with one that combines two of my favourites: stack profiling and “twittershooting” (collective troubleshooting using Twitter as a collaboration tool). The database in question is a 3-node RAC cluster, Oracle version 18.11 being upgraded to 19.10. The problem was detected during the pre-upgrade testing with “compatible” parameter set to 18 (that part was essential for the backout plan in case of major post-upgrade complications). I mention this because for whatever reason, the problem only showed up when the parameter was set.
Continue reading “Performance issues around GTT in 19c”
Oracle Diagnostician 