FileContentEntry
    hash              FileContentReference
    ix                Natural
    chunkHash         FileContentChunkId
    UniqueFileContentEntry hash ix

FileContentChunk
    hash              FileContentChunkReference
    content           ByteString
    contentBased      Bool default=false -- For Migration
    Primary           hash

FileContentChunkUnreferenced
    hash              FileContentChunkId
    since             UTCTime
    UniqueFileContentChunkUnreferenced hash

SessionFile
    content         FileContentReference Maybe
    touched         UTCTime

FileLock
    content         FileContentReference
    instance        InstanceId
    time            UTCTime

FileChunkLock
    hash            FileContentChunkReference
    instance        InstanceId
    time            UTCTime