Prompt
Help us change the DB schema according to the goals and data below. [input] Goals and usage situations: I would like to resolve the stuck point in changing the DB schema and decide the next action. Resources to review: Existing schema and changes required Conditions and Constraints: Please proceed based on the provided data, and mark any missing facts as requiring confirmation. Previous attempts and records: This is my first attempt. Please proceed from the parts that can be confirmed in the current data. [Key points to check in this topic] Check the order of compatibility, backfill, lock, verification, and recovery. [Results to be created this time] Design indicators and logs to distinguish between success, failure, and delay. For each signal, attach the data source, observation location, and order of investigation in case of abnormality. Instead of putting sensitive values in logs, separate the probable cause from the observed facts. [Working Principle] Give priority to facts confirmed in the current environment and provided code. Don't create APIs/files/tests that don't exist. Treat sensitive values as hidden examples and leave unexecuted tasks as unexecuted. If there is no input that will change the results, ask only the necessary questions first and proceed with the parts that can be confirmed with data. [Completion criteria] When a problem occurs, check whether it is possible to tell by signal which stage the blockage occurred. Distinguish between the basis for the outcome, remaining uncertainties, and next actions, and mark only what has actually been confirmed as complete.