मुझे विश्वास है कि आप यह चाहते थे:
SELECT to_char(revision_timestamp, 'YYYY-MM'),
count(b.id)
FROM package a
JOIN package_revision b ON a.revision_id = b.revision_id
WHERE revision_timestamp >
date_trunc('month', CURRENT_DATE) - INTERVAL '1 year'
GROUP BY 1
