I would create only one query:
DELETE FROM mytable
WHERE company in (
SELECT Company
FROM (
SELECT Company,
COUNT(CASE WHEN value IS NULL THEN 1 END)
OVER (PARTITION BY company ORDER BY id
ROWS BETWEEN CURRENT ROW AND 2 FOLLOWING) As cnt,
COUNT(CASE WHEN value IS NULL THEN 1 END)
OVER (PARTITION BY company)
/
COUNT(*)
OVER (PARTITION BY company) As p50
) alias
WHERE cnt >= 3 OR p50 > 0.5
)
A composite index on (company + value) columns can help to gain a maximum speed of this query.
EDIT
The above query doesn't work
I've corrected it slightly, here is a demo: http://sqlfiddle.com/#!15/c9bfe/7
Two things have been changed:
- PARTITION BY company ORDER BY date instead of ORDER BY id
- explicit cast to numeric( because integer have been truncated to 0):
OVER (PARTITION BY company)::numeric
SELECT company, cnt, p50
FROM (
SELECT company,
COUNT(CASE WHEN value IS NULL THEN 1 END)
OVER (PARTITION BY company ORDER BY date
ROWS BETWEEN CURRENT ROW AND 2 FOLLOWING) As cnt,
SUM(CASE WHEN value IS NULL THEN 1 ELSE 0 END)
OVER (PARTITION BY company)::numeric
/
COUNT(*)
OVER (PARTITION BY company) As p50
FROM mytable
) alias
-- WHERE cnt >= 3 OR p50 > 0.5
and now the delete query should work:
DELETE FROM mytable
WHERE company in (
SELECT company
FROM (
SELECT company,
COUNT(CASE WHEN value IS NULL THEN 1 END)
OVER (PARTITION BY company ORDER BY date
ROWS BETWEEN CURRENT ROW AND 2 FOLLOWING) As cnt,
SUM(CASE WHEN value IS NULL THEN 1 ELSE 0 END)
OVER (PARTITION BY company)::numeric
/
COUNT(*)
OVER (PARTITION BY company) As p50
FROM mytable
) alias
WHERE cnt >= 3 OR p50 > 0.5
)