Extracting database schemas from PostgreSQL

The fgldbsch database schema extractor can only extract the schema from a PostgreSQL database if you specify the namespace of tables with the -ow option.

PostgreSQL distinguishes table owners from table schemas, with the concept of namespaces.

Tip: In PostgreSQL system catalogs, the namespace of a table is defined by the pg_class.relnamespace column. This column contains the oid that references a namespace in the pg_namespace system table.

For PostgreSQL, the fgldbsch -ow option will specify the PostgreSQL namespace, instead of the owner of the table, because a database user can create several namespaces and use the same table name in those different namespaces. Filtering schema extraction on the table owner would mix up table definitions from different schemas/namespaces.

When extracting a database schema from a PostgreSQL database, you must specify the namespace of tables with the -ow option. If no -ow option is provided and the -un option is specified, fgldbsch will use the login name of the -un option as namespace. If neither -ow, nor -up options are specified, fgldbsch will use the PostgreSQL "public" namespace by default.

Since database tables are usually created in the "public" namespace, you typically specify this namespace with the -ow option:

fgldbsch -db test1 -dv dbmpgs -un pgsuser -up fourjs -v -ow public