Use NOT VALID to enforce a not null constraint on file_store

When adding a constraint to a table, we can optionally include
NOT VALID. This tells Postgres that it doesn’t need to enforce
the constraint on existing records in the table. At least not
immediately. This constraint will be enforced for any updates
and subsequent insertions. Thus, we can immediately enforce
the constraint while giving ourselves time to clean up any
existing records that conflict with the constraint.

db/migrate/20200406165950_add_not_null_constraint_on_file_store_to_lfs_objects.rb

+# frozen_string_literal: true
+
+class AddNotNullConstraintOnFileStoreToLfsObjects < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  CONSTRAINT_NAME = 'lfs_objects_file_store_not_null'
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE lfs_objects ADD CONSTRAINT #{CONSTRAINT_NAME} CHECK (file_store IS NOT NULL) NOT VALID;
+      SQL
+    end
+  end
+
+  def down
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE lfs_objects DROP CONSTRAINT IF EXISTS #{CONSTRAINT_NAME};
+      SQL
+    end
+  end
+end

db/migrate/20200406171857_add_not_null_constraint_on_file_store_to_ci_job_artifacts.rb

+# frozen_string_literal: true
+
+class AddNotNullConstraintOnFileStoreToCiJobArtifacts < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  CONSTRAINT_NAME = 'ci_job_artifacts_file_store_not_null'
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE ci_job_artifacts ADD CONSTRAINT #{CONSTRAINT_NAME} CHECK (file_store IS NOT NULL) NOT VALID;
+      SQL
+    end
+  end
+
+  def down
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE ci_job_artifacts DROP CONSTRAINT IF EXISTS #{CONSTRAINT_NAME};
+      SQL
+    end
+  end
+end

db/migrate/20200406172135_add_not_null_constraint_on_file_store_to_uploads.rb

+# frozen_string_literal: true
+
+class AddNotNullConstraintOnFileStoreToUploads < ActiveRecord::Migration[6.0]
+  include Gitlab::Database::MigrationHelpers
+
+  CONSTRAINT_NAME = 'uploads_store_not_null'
+  DOWNTIME = false
+
+  def up
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE uploads ADD CONSTRAINT #{CONSTRAINT_NAME} CHECK (store IS NOT NULL) NOT VALID;
+      SQL
+    end
+  end
+
+  def down
+    with_lock_retries do
+      execute <<~SQL
+        ALTER TABLE uploads DROP CONSTRAINT IF EXISTS #{CONSTRAINT_NAME};
+      SQL
+    end
+  end
+end

db/structure.sql

@@ -7697,6 +7697,9 @@ ALTER TABLE ONLY public.ci_daily_report_results
 ALTER TABLE ONLY public.ci_group_variables
     ADD CONSTRAINT ci_group_variables_pkey PRIMARY KEY (id);
 
+ALTER TABLE public.ci_job_artifacts
+    ADD CONSTRAINT ci_job_artifacts_file_store_not_null CHECK ((file_store IS NOT NULL)) NOT VALID;
+
 ALTER TABLE ONLY public.ci_job_artifacts
     ADD CONSTRAINT ci_job_artifacts_pkey PRIMARY KEY (id);
 
@@ -8054,6 +8057,9 @@ ALTER TABLE ONLY public.ldap_group_links
 ALTER TABLE ONLY public.lfs_file_locks
     ADD CONSTRAINT lfs_file_locks_pkey PRIMARY KEY (id);
 
+ALTER TABLE public.lfs_objects
+    ADD CONSTRAINT lfs_objects_file_store_not_null CHECK ((file_store IS NOT NULL)) NOT VALID;
+
 ALTER TABLE ONLY public.lfs_objects
     ADD CONSTRAINT lfs_objects_pkey PRIMARY KEY (id);
 
@@ -8447,6 +8453,9 @@ ALTER TABLE ONLY public.u2f_registrations
 ALTER TABLE ONLY public.uploads
     ADD CONSTRAINT uploads_pkey PRIMARY KEY (id);
 
+ALTER TABLE public.uploads
+    ADD CONSTRAINT uploads_store_not_null CHECK ((store IS NOT NULL)) NOT VALID;
+
 ALTER TABLE ONLY public.user_agent_details
     ADD CONSTRAINT user_agent_details_pkey PRIMARY KEY (id);
 
@@ -13127,6 +13136,9 @@ COPY "schema_migrations" (version) FROM STDIN;
 20200403185127
 20200403185422
 20200406135648
+20200406165950
+20200406171857
+20200406172135
 20200406192059
 20200407094005
 20200407094923