fix(redshift): list schemas via pg_namespace + has_schema_privilege

[datlechin]

Fixes #971.

Summary

On Redshift, the schema switcher was empty for non-admin users — so users were stuck on whatever schema they connected with, with no way to switch.

Root cause

RedshiftPluginDriver.fetchSchemas queried information_schema.schemata. On Redshift this view returns only schemas the current user owns — Redshift diverges from PostgreSQL here, where USAGE alone is enough. Result: a typical role with USAGE on a few schemas saw zero entries in the dropdown.

The SET search_path path was already correct; the bug was upstream in the schema listing query.

Repro (verified)

Redshift Serverless workgroup, non-admin role with GRANT USAGE ON SCHEMA analytics, reporting:

-- old query (information_schema.schemata)
(0 rows)

-- new query (pg_namespace + has_schema_privilege)
analytics
public
reporting

Fix

Single-file SQL swap in Plugins/PostgreSQLDriverPlugin/RedshiftPluginDriver.swift:

SELECT nspname FROM pg_namespace
WHERE nspname NOT LIKE 'pg_%'
  AND nspname <> 'information_schema'
  AND has_schema_privilege(current_user, nspname, 'USAGE')
ORDER BY nspname

pg_namespace lists every schema in the database; has_schema_privilege(..., 'USAGE') filters to those the role can actually use. Same query works for admin (owner implicitly has USAGE) and non-admin alike.

PostgreSQL's fetchSchemas is intentionally untouched — information_schema.schemata does the right thing on real Postgres, where USAGE is sufficient.

Test plan

• Connect to a Redshift cluster as a non-admin role with USAGE on a subset of schemas
• Open ⌘K schema switcher
• Confirm all USAGE-granted schemas appear (previously empty)
• Switch to one of them, confirm sidebar refreshes to that schema's tables
• Connect as admin, confirm schema list still complete
• Connect to a real PostgreSQL instance, confirm its schema list still complete (untouched code path)

[chatgpt-codex-connector]

You have reached your Codex usage limits for code reviews. You can see your limits in the Codex usage dashboard.