Hello.. How to handle multiple DB copying from

tap-postgres

 to 

target-bigquery

? Can I keep multiple meltano.yml like meltano_A.yml and meltano_B.yml? how to maintain DB credentials in .env file? or Do I need to create separate meltano projects for different DBs?

I personally have not worked with

tap-postgres

but I think you can use plugin inheritance to create multiple extractors for the different databases. You can use

inherit_from

and point that to your generic postgres extractor. https://meltano.com/docs/project.html#inheriting-plugin-definitions

Jules is correct. Then environment variables can be set based on the plugin name https://meltano.com/docs/configuration.html#environment-variables