Describe the bug

While upgrading to 0.6.4 from 0.6.3, we hit an issue that is similar to #350 but for a postgres target that had foreign data wrappers set up while using get_relations_by_pattern

Steps to reproduce

Setup an imported schema extdb_extschema in postgres target database with table that matches '%_'+table_suffix.

Reference in model to get_relations_by_pattern:

{% set relations = dbt_utils.get_relations_by_pattern(schema_pattern='extdb__extschema',
                                                      table_pattern='%_'+table_suffix,
                                                      database=this.database) %}

Run dbt compile on model for target database

Expected results

The successfully retrieves the set of relations to iterate over creating a single model out of the records in the matching tables (e.g. union all of matching relations).

This is the current result when running dbt utils 0.6.3

Actual results

Unhandled runtime errors occur during the get_relations_by_pattern call causing the model to not build.

Screenshots and log output

Unhandled error while executing model.test_model.consolidation
Field "type" of type typing.Union[dbt.contracts.relation.RelationType, NoneType] in dbt.adapters.postgres.relation.PostgresRelation has invalid value 'foreign'

System information

The contents of your packages.yml file:

packages:
  - package: fishtown-analytics/dbt_utils
    version: 0.6.4

dbt version: 0.19.1

Which database are you using dbt with?

• postgres
• redshift
• bigquery
• snowflake
• other (specify: ____________)

The output of dbt --version:

installed version: 0.19.1
   latest version: 0.19.1

Up to date!

Plugins:
  - snowflake: 0.19.1
  - redshift: 0.19.1
  - bigquery: 0.19.1
  - postgres: 0.19.1

Additional context

The addition of table_type into the default__get_tables_by_pattern_sql macro causes problems with foreign tables in postgres since they have a type of FOREIGN in information_schema, but dbt doesn't support that type by that name.

Are you interested in contributing the fix?

Yeah. I'm not sure if there are any caveats about what the external type means in dbt core or weird downstream effects of it, but a similar fix to #351 should solve the problem unless there are concerns about ramifications in other adapters.