Thanks for the PR!
But the index definition has to be done in the xml files that specify the schema `src/lib/srdb1/schema/pr_watchers.xml` -- repo link:
* https://github.com/kamailio/kamailio/blob/master/src/lib/srdb1/schema/pr_wat...
The the sql/db creation scripts can be generated for all backends (mysql, postgres, ...) with:
``` make dbschema ```
You would need xml tools installed, you can just change the xml file and I can then regenerated the sql/db scripts.
You can force push to this PR or close and open another one.