Where Problems Show Up

Problem Area	What’s Happening Under the Hood
Query runs forever	Bad access path (for example: full table scan)
Query never returns	Execution stuck on lock, contention, or temp space
Query used to be fast	Execution plan changed (due to stats, bind peeking)
Query runs fast once	Plan got cached or parallelism kicked in by chance
System is overloaded	Too many concurrent queries, bad query patterns