Add migration to rename primary keys

[ci skip]

db/migrate/20190502102512_ensure_postgres_index_names.rb

@@ -0,0 +1,32 @@
+class EnsurePostgresIndexNames < ActiveRecord::Migration[5.2]
+  def up
+    if OpenProject::Database.mysql?
+      warn "You're using MySQL, skipping index renaming. You will need to re-run this when switching to PostgreSQL"
+    end
+
+    sql = <<~SQL
+      SELECT
+        FORMAT('%s_pkey', table_name) as new_name,
+        constraint_name as old_name
+      FROM information_schema.table_constraints
+      WHERE UPPER(constraint_type) = 'PRIMARY KEY'
+      AND constraint_name != FORMAT('%s_pkey', table_name)
+      ORDER BY table_name;
+    SQL
+
+    ActiveRecord::Base.connection.execute(sql).each do |entry|
+      old_name = entry['old_name']
+      new_name = entry['new_name']
+
+      begin
+        execute %(ALTER INDEX "#{old_name}" RENAME TO #{new_name};)
+      rescue StandardError => e
+        warn "Failed to rename index #{old_name} to #{new_name}: #{e.message}. Skipping"
+      end
+    end
+  end
+
+  def down
+    # Nothing to do
+  end
+end

docker/mysql-to-postgres/bin/migrate-mysql-to-postgres

@@ -131,6 +131,19 @@ if check_status != 0
   exit 1
 end
 
+# We need to ensure primary keys get renamed to `<table_name>_pkey`
+# because pgloader uses unique index names and we will otherwise be unable
+# to rename them in the future
+puts "Renaming primary keys"
+
+_, redo_status = run "bundle exec rake db:migrate:redo VERSION=20190502102512", record_output: false
+
+if redo_status != 0
+  puts "\nRenaming of indices for PostgreSQL failed. See above."
+
+  exit 1
+end
+
 # if the version was present on MySQL already we need to redo it to
 # add the postgres specific columns.
 needs_fulltext_migration = check_output.include?("true")