Spend most of my time in a db2 environment as a DA/DBA. From time to time I also work with other DBMS such as mysql, psql, mssql.
I have a couple of Db2-utilities at github, that you may or may not find useful:
https://github.com/lelle1234/Db2Utils/
DBParser, creates ddl for a database. Output is supposed to be in topological order
IndexAdvisor, investigates all possible index combinations for a query