Is there some risk for data to change the type of the column of the
non-empty table.
I need only longer string than now.

alter table fakt alter poznamka type string_80;

now it is poznamka = string_30;

Or is better to do it with temporary column

poznamka -> temp_30
drop poznamka
add poznamka string_80
temp_30 -> poznamka
drop temp_30

???

Thank You, Tom