What is the relationship between field_data_field_ and field_revision_ tables?
{field_data_[field_name]}
  
  Standard data storage for a field. It's recommended you use
  _field_sql_storage_tablename to get the name of this table.
  
  {field_revision_[field_name]}
  
  Standard revision storage for a field. It is recommended to use
  _field_sql_storage_revision_tablename to get the name of this table.


For more details