There are already ways to see execution plan This is very true. And for day to day use, they are more then sufficient. But sometimes the tools don't show the functions/conditions correctly. And some details are never present (e.g. in complex plans with multiple materialized subqueries, it's sometimes impossible to determine from which copy of a table/subquery a column comes). (And out of scope of this series, you may want to see bind values, or to know which line in the plan you are on = which (copy of) table is oracle just reading.) Examples in this blog are necessarily simple ones; and in such examples we see cases where the added value of such access to execution plan is not very high. But never forget that this can be extended to much more complex cases. Existing tools EXPLAIN PLAN EXPLAIN PLAN is long time with us. The main problem is that it shows plan for a new parse - and this can be different than what a session is actually executing, as it depends on b...
I use this blog to publish the small bits I come accross when using the Oracle Database. It's the "every day I learn something new" style.