You will need to rewrite or cast the expression.

In PostgreSQL, if you encounter the error "You will need to rewrite or cast the expression", it means that the database is unable to implicitly convert or cast the expression to the desired data type.

To resolve this issue, you have a few options:

1. Use explicit casting: If you know the desired data type for the expression, you can use explicit casting to convert it. For example:

   SELECT column_name::desired_data_type FROM table_name;

Replace `column_name` with the actual column name and `desired_data_type` with the appropriate data type, such as `integer`, `text`, etc.

2. Modify the expression: If the expression is not compatible with the desired data type, you might need to modify it. This could involve changing operators, functions, or performing additional calculations to achieve the desired result.

3. Use a different function or operator: If the current function or operator is causing the error, you can try using a different function or operator that is compatible with the desired data type.

It's important to review the specific error message and the context in which it occurs to determine the best course of action. Refer to the PostgreSQL documentation for more information on data type casting and available functions/operators.