The EXPLAIN keyword is really awesome. It also allows you to quickly validate SQLite command text without actually executing it. We have found this to be useful for real-time validation of user inputs when working on SQL-based config tools.
Note that EXPLAIN also seamlessly incorporates any application-defined functions, so you can validate everything is as expected. Useful when being clever with DSLs and such.
I hope SQLite's EXPLAIN were more visual / tree-like. Using bytecode internally is fine, but what users care is typically more high level. Decoding the that high level intention from the bytecode is so burdensome that I often give up and just fall back to try-n-error.
Note that EXPLAIN also seamlessly incorporates any application-defined functions, so you can validate everything is as expected. Useful when being clever with DSLs and such.