Explain plan for slow database queries

[vvydier]

I would like to add additional/extended information for a db-span when a slow query is made to a database (I am currently looking to add this functionality for MySQL where all you need to do is to re-send the SQL query with EXPLAIN pre-pended).
For a slow database query, this additional info will be added as an additional attribute/event with the EXPLAIN output in the current db-span (and not as another span). This is something that will be off by default (for performance reasons, but can be turned on if there is a need to investigate why a database is returning data slowly).
What is the best way to achieve this in Otel-js and is there an example in other language agents/a prototype or that I can look at. Thanks