SchemaCrawler for PostgreSQL will allow you to do the diffs. With
SchemaCrawler for PostgreSQL, you can take human-readable snapshots
of the schema and data, for later comparison. SchemaCrawler outputs
details of your schema (tables, views, procedures, and more) in a diff-
able plain-text format (text, CSV, or XHTML). You can order data
alphabetically, or by ordinal order. SchemaCrawler can also output
data (including CLOBs and BLOBs) in the same plain-text formats.
SchemaCrawler for PostgreSQL is free and open-source (under the GPL),
and is available at SourceForge: http://schemacrawler.sourceforge.net/
Sualeh Fatehi.