040000 tree 447e0ec8a2bb79b6aa361affc0aadc36b7fa6fd9	locking
040000 tree f16a6ff7c901c2f1fa0d04b9619a2d94e23279c6	logging
040000 tree 771f161a7488d3c8c91712dc8572903f79af915d	recovery
040000 tree c39a334b631aea4c82464222e2a4823c4d0f8bdb	transaction