Please check out the following community article which explains the steps to migrate. https://community.snowflake.com/s/article/PostgreSQL-to-Snowflake-ETL-Steps-to-Migrate-Data

This is from one of the Snowflake partners who provides the tools to migrate the data.

I went through this a couple of months ago and will share what I learned.

1. Snowflake does not recognize psql so a psql export/import will not work.
2. The recommendation I received from support was to export the tables as csv files, recreate the DDL, and then stage the csv files in S3.
3. There are third party tools that help connect and sync Postgres databases to Snowflake. Stitch being the one my group looked at.

So you can write your own integration or use Stitch to connect the two. There could be a more effective way to do this but if you are moving a large database over, I am afraid there is not an easy way to do this. That said, it is not terribly difficult but will take time to move everything over. Hope that helps!