Add Redshift behavior change: restrict_direct_pg_catalog_access

website/docs/reference/global-configs/behavior-changes.md

@@ -61,6 +61,7 @@ When we use dbt Cloud in the following table, we're referring to accounts that h
 | require_explicit_package_overrides_for_builtin_materializations | 2024.04.141      | 2024.06.192         | 1.6.14, 1.7.14  | 1.8.0             |
 | require_resource_names_without_spaces                           | 2024.05.146      | TBD*                | 1.8.0           | 1.9.0             |
 | source_freshness_run_project_hooks                              | 2024.03.61       | TBD*                | 1.8.0           | 1.9.0             |
+| [Redshift] restrict_direct_pg_catalog_access                    | 2024.09.242      | TBD*                | dbt-redshift v1.9.0           | 1.9.0             |
 
 When the dbt Cloud Maturity is "TBD," it means we have not yet determined the exact date when these flags' default values will change. Affected users will see deprecation warnings in the meantime, and they will receive emails providing advance warning ahead of the maturity date. In the meantime, if you are seeing a deprecation warning, you can either:
 - Migrate your project to support the new behavior, and then set the flag to `True` to stop seeing the warnings.
@@ -121,3 +122,11 @@ on-run-start:
   - '{{ ... if flags.WHICH != 'freshness' }}'
 ```
 </File>
+
+## Adapter-specific behavior changes
+
+### [Redshift] restrict_direct_pg_catalog_access
+
+Originally, the `dbt-redshift` adapter was built on top of the `dbt-postgres` adapter. It leveraged several Postgres tables for accessing metadata. When this flag is enabled, instead of using `pg_` tables, the adapter will use either the Redshift API (via the Python client) if available, and otherwise query tables in Redshift's `information_schema`.
+
+While we don't intend for there to be any user-noticeable behavior changes as a result of this change, out of an abundance of caution, we are gating it behind a behavior-change flag and encouraging users to test it out before it becomes the default for everyone.