I eventually managed to answer my previous question (https://groups.google.com/forum/?utm_medium=email&utm_source=footer#!topic/scalaquery/2c3r-0zj7tk
) - I now have Postgres configured with the 'lo' extension and everything appears to be working on the database side. The problem I have now is that when I try to access the fields later in the Scala code, e.g. converting a Clob or Blob to a string, I get an error message about large objects requiring transactions, even though the table row was originally retrieved as part of a transaction. It looks to me like the Postgres JDBC driver (or maybe Slick itself) is effectively lazy-loading the large objects. Is there a way to disable this behavior? Alternately, is there a way I could map Clob and Blob to the Postgres BYTEA type instead? I don't mind customizing PostgresProfile if that's what it takes, but it's unclear to me how to do this.