remove time_from_last_post column from articles table
SELECT AVGtime_from_last_post) FROM articles WHERE feed_id=24;
gives:
avg
-----------------------
1040.6154083742916230
but:
WITH tflp AS (
SELECT
EXTRACT(EPOCH FROM (stamp - LAG(stamp, 1) OVER (ORDER BY stamp))) AS tflp
FROM articles where feed_id=24)
SELECT AVG(tflp) FROM tflp;
also yields:
avg
------------------
1040.62938293158