Or, using the same table and data, the correlated form:
```
select ordering_column,
coalesce(ip_24_temperature,
(
select ip_24_temperature
from weather_table
where ordering_column < o.ordering_column
and ip_24_temperature is not null
order by ordering_column desc
limit 1
),
0
) as ip_24_temperature,
coalesce(ip_24_humidity,
(
select ip_24_humidity
from weather_table
where ordering_column < o.ordering_column
and ip_24_humidity is not null
order by ordering_column desc
limit 1
),
0
) as ip_24_humidity
from weather_table as o
order by ordering_column
;
```
For swiftest performance (at the expense, as always, of disk space), add the following indexes:
```
create index idx_weather_temperature on weather_table (ordering_column, ip_24_temperature) where ip_24_temperature is not null;
create index idx_weather_humidity on weather_table (ordering_column, ip_24_humidity) where ip_24_humidity is not null;
```