Updates random array in batches of 1000 records

update_random_array.sql

do $$
declare	
   row_count integer := 449166;
   batch_size integer := 1000;
   offset_value integer := 0;
begin
	while row_count > 0 loop
	
	update 
        my_table 
    set array_column = ('{' || regexp_replace(repeat((array['X,', 'Y,X,', 'T,X,C,', 'T,Y,', 'Z,'])[floor(random() * 4 + 1)], floor(random() * 3 + 1)::integer), '.$', '') || '}')::varchar[] 
    where id in (select id from my_table offset offset_value limit batch_size);
	
    raise notice 'Row remaining %', row_count ;
	
    row_count := row_count - batch_size;
	offset_value := offset_value + batch_size;
	end loop;
end; $$