Remove namespaces.plan_id column

This column is unused and already ignored in the previous release

changelogs/unreleased/196862-drop-plan-id.yml

+---
+title: Remove namespaces.plan_id column
+merge_request: 30351
+author:
+type: other

db/post_migrate/20200424043515_drop_namespaces_plan_id.rb

+# frozen_string_literal: true
+
+class DropNamespacesPlanId < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  disable_ddl_transaction!
+
+  def up
+    with_lock_retries do # rubocop: disable Migration/WithLockRetriesWithoutDdlTransaction
+      remove_column :namespaces, :plan_id
+    end
+  end
+
+  def down
+    unless column_exists?(:namespaces, :plan_id)
+      with_lock_retries do # rubocop: disable Migration/WithLockRetriesWithoutDdlTransaction
+        add_column :namespaces, :plan_id, :integer
+      end
+    end
+
+    add_concurrent_index :namespaces, :plan_id
+    add_concurrent_foreign_key :namespaces, :plans, column: :plan_id, on_delete: :nullify
+  end
+end

db/structure.sql

@@ -4100,7 +4100,6 @@ CREATE TABLE public.namespaces (
     require_two_factor_authentication boolean DEFAULT false NOT NULL,
     two_factor_grace_period integer DEFAULT 48 NOT NULL,
     cached_markdown_version integer,
-    plan_id integer,
     project_creation_level integer,
     runners_token character varying,
     trial_ends_on timestamp with time zone,
@@ -9893,8 +9892,6 @@ CREATE INDEX index_namespaces_on_path ON public.namespaces USING btree (path);
 
 CREATE INDEX index_namespaces_on_path_trigram ON public.namespaces USING gin (path public.gin_trgm_ops);
 
-CREATE INDEX index_namespaces_on_plan_id ON public.namespaces USING btree (plan_id);
-
 CREATE UNIQUE INDEX index_namespaces_on_push_rule_id ON public.namespaces USING btree (push_rule_id);
 
 CREATE INDEX index_namespaces_on_require_two_factor_authentication ON public.namespaces USING btree (require_two_factor_authentication);
@@ -11332,9 +11329,6 @@ ALTER TABLE ONLY public.system_note_metadata
 ALTER TABLE ONLY public.merge_requests
     ADD CONSTRAINT fk_fd82eae0b9 FOREIGN KEY (head_pipeline_id) REFERENCES public.ci_pipelines(id) ON DELETE SET NULL;
 
-ALTER TABLE ONLY public.namespaces
-    ADD CONSTRAINT fk_fdd12e5b80 FOREIGN KEY (plan_id) REFERENCES public.plans(id) ON DELETE SET NULL;
-
 ALTER TABLE ONLY public.project_import_data
     ADD CONSTRAINT fk_ffb9ee3a10 FOREIGN KEY (project_id) REFERENCES public.projects(id) ON DELETE CASCADE;
 
@@ -13562,6 +13556,7 @@ COPY "schema_migrations" (version) FROM STDIN;
 20200423080607
 20200423081409
 20200423101529
+20200424043515
 20200424050250
 20200427064130
 \.