Add Updated_At column to Merge Requests

This will enable us to see when the status of a merge request last changed.

deployment/hasura/migrations/AerieMerlin/36_metadata_updated_at/down.sql

@@ -0,0 +1,5 @@
+drop trigger set_timestamp on merge_request;
+drop function merge_request_set_updated_at();
+alter table merge_request drop column updated_at;
+
+call migrations.mark_migration_rolled_back('36');

deployment/hasura/migrations/AerieMerlin/36_metadata_updated_at/up.sql

@@ -0,0 +1,17 @@
+alter table merge_request add column updated_at timestamptz not null default now();
+
+create function merge_request_set_updated_at()
+returns trigger
+security definer
+language plpgsql as $$begin
+  new.updated_at = now();
+  return new;
+end$$;
+
+create trigger set_timestamp
+  before update or insert on merge_request
+  for each row
+execute function merge_request_set_updated_at();
+
+call migrations.mark_migration_applied('36');
+

merlin-server/sql/merlin/applied_migrations.sql

@@ -38,3 +38,4 @@ call migrations.mark_migration_applied('32');
 call migrations.mark_migration_applied('33');
 call migrations.mark_migration_applied('34');
 call migrations.mark_migration_applied('35');
+call migrations.mark_migration_applied('36');

merlin-server/sql/merlin/tables/merge_request.sql

@@ -7,6 +7,7 @@ create table merge_request(
       status merge_request_status default 'pending',
       requester_username text,
       reviewer_username text,
+      updated_at timestamptz not null default now(),
       constraint merge_request_requester_exists
         foreign key (requester_username)
         references metadata.users
@@ -39,3 +40,16 @@ comment on column merge_request.requester_username is e''
   'The user who created this merge request.';
 comment on column merge_request.reviewer_username is e''
   'The user who reviews this merge request. Is empty until the request enters review.';
+
+create function merge_request_set_updated_at()
+returns trigger
+security definer
+language plpgsql as $$begin
+  new.updated_at = now();
+  return new;
+end$$;
+
+create trigger set_timestamp
+  before update or insert on merge_request
+  for each row
+execute function merge_request_set_updated_at();