CREATE TABLE IF NOT EXISTS files (
    id serial,
    file_id varchar(255) not null unique,
    file_name varchar(255) not null,
    valid_till timestamp not null,
    kind varchar(255) not null,
    primary key (id)
);

ALTER TABLE files ADD COLUMN IF NOT EXISTS delete_on_download boolean;
ALTER TABLE files ALTER COLUMN delete_on_download set not null;
ALTER TABLE files ALTER COLUMN valid_till TYPE timestamptz;
ALTER TABLE files ADD COLUMN IF NOT EXISTS content_type varchar(255);
UPDATE files set content_type = 'text/plain' where kind = 'text';
UPDATE files set content_type = 'application/octet-stream' where kind = 'binary';
ALTER TABLE files ALTER COLUMN content_type set not null;
ALTER TABLE files DROP COLUMN IF EXISTS kind;