How to integrate postgreSql with DAML application?

I am planning to deploy the daml application on postgreSQL based ledger. I am not getting any information on any forum.

If you are referring to deploying Canton itself, the documentation has an entire section on how to deploy Canton, starting from how, what and where to download Canton, and including a page specifically on using PostgreSQL. This page and the whole section around it documents deployment, with a further section down below on operational concerns.

If you are referring to uploading Daml models on Canton, you will want to have a look at this section on using the Canton Console to upload and manage DARs. The specifics of how this needs to happen depend on your specific deployment and you need to contact the participant operator for specific details.

If you are referring to your own application talking to the ledger, that is an off-ledger concern that is specific to the operator of the infrastructure where you want to deploy your application. As an example, Daml Hub is an integrated offering that has specific instructions on deploying off-ledger services that communicate with Daml models. I can expect other offerings to more often than not have nothing specific to Daml, in which case you will have to deploy your application and manage its configuration by yourself.