Changing the type of a column in planetscale

ensure all data in the existing column is compatible with the new type

add new column with a temporary name and desired type

copy data in existing column to temp column with raw SQL

delete existing column and any indexes it is used in (making a note of the indexes)

add a column with the same type as the temporary column and the original name

add back any indexes with the new column

copy data from the temporary column to the new column

add any needed constraints back to the new column (e.g. NOT NULL)

delete the temporary column

reorder columns back to original order if required