Make db:schema:load an atomic transaction

[jakemiller13]

ref: https://stackoverflow.com/questions/78110476/is-loading-structure-sql-using-rake-an-atomic-transaction

---

If I load structure.sql using this command and it fails because of an error within the structure.sql file:

$ bundle exec rake db:schema:load RAILS_ENV=test

psql:/path/to/app/db/structure.sql:13342: ERROR:  column "column_id" does not exist
rake aborted!
failed to execute:
psql --set ON_ERROR_STOP=1 --quiet --no-psqlrc --output /dev/null --file /path/to/app/db/structure.sql test

Please check the output above for any errors and make sure that `psql` is installed in your PATH and has proper permissions.

/Users/jmiller/.rbenv/versions/2.7.6/bin/bundle:23:in `load'
/Users/jmiller/.rbenv/versions/2.7.6/bin/bundle:23:in `<main>'
Tasks: TOP => db:schema:load
(See full trace by running task with --trace)

and then attempt to rerun after resolving the error, it fails again due to an existing enum type that is defined within structure.sql:

$ bundle exec rake db:schema:load RAILS_ENV=test 

psql:/path/to/app/db/structure.sql:33: ERROR:  type "status" already exists
rake aborted!
failed to execute:
psql --set ON_ERROR_STOP=1 --quiet --no-psqlrc --output /dev/null --file /path/to/app/db/structure.sql test

Please check the output above for any errors and make sure that `psql` is installed in your PATH and has proper permissions.

/Users/jmiller/.rbenv/versions/2.7.6/bin/bundle:23:in `load'
/Users/jmiller/.rbenv/versions/2.7.6/bin/bundle:23:in `<main>'
Tasks: TOP => db:schema:load
(See full trace by running task with --trace)

This enum type could only exist if the structure.sql got loaded in some capacity, and therefore suggests that it is a non-atomic transaction. This can cause odd an unexpected database states.

It looks like rake db:schema:dump ultimately calls pg_dump:

      def structure_dump(filename, extra_flags)
        search_path = \
          case ActiveRecord.dump_schemas
          when :schema_search_path
            configuration_hash[:schema_search_path]
          when :all
            nil
          when String
            ActiveRecord.dump_schemas
          end

        args = ["--schema-only", "--no-privileges", "--no-owner"]
        args.concat(["--file", filename])

        args.concat(Array(extra_flags)) if extra_flags

        unless search_path.blank?
          args += search_path.split(",").map do |part|
            "--schema=#{part.strip}"
          end
        end

        ignore_tables = ActiveRecord::SchemaDumper.ignore_tables
        if ignore_tables.any?
          args += ignore_tables.flat_map { |table| ["-T", table] }
        end

        args << db_config.database
        run_cmd("pg_dump", args, "dumping")
        remove_sql_header_comments(filename)
        File.open(filename, "a") { |f| f << "SET search_path TO #{connection.schema_search_path};\n\n" }
      end

Therefore, bundle exec rake db:schema:load should be able to be called with the --single-transaction flag per pg_restore ( https://www.postgresql.org/docs/current/app-pgrestore.html ), potentially by adding to the array here:

      def structure_load(filename, extra_flags)
        args = ["--set", ON_ERROR_STOP_1, "--quiet", "--no-psqlrc", "--output", File::NULL, "--file", filename]
        args.concat(Array(extra_flags)) if extra_flags
        args << db_config.database
        run_cmd("psql", args, "loading")
      end

[Hiroshi SHIBATA]

I'm not sure what's rake issue. You mixed Rails and Rake responsibility.