Re: efficient data reduction (and deduping)
| От | Alessandro Gagliardi |
|---|---|
| Тема | Re: efficient data reduction (and deduping) |
| Дата | |
| Msg-id | CAAB3BBL_6ju5QS2qEbmRAtePN2BOi==dBig925RjXH2QyyGzwA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: efficient data reduction (and deduping) (Claudio Freire <klaussfreire@gmail.com>) |
| Ответы |
Re: efficient data reduction (and deduping)
|
| Список | pgsql-performance |
Interesting solution. If I'm not mistaken, this does solve the problem of having two entries for the same user at the exact same time (which violates my pk constraint) but it does so by leaving both of them out (since there is no au1.hr_timestamp > au2.hr_timestamp in that case). Is that right?
On Thu, Mar 1, 2012 at 10:35 AM, Claudio Freire <klaussfreire@gmail.com> wrote:
Try
INSERT INTO hourly_activity
SELECT ... everything from au1 ...
FROM activity_unlogged au1
LEFT JOIN activity_unlogged au2 ON au2.user_id = au1.user_id
AND
date_trunc('hour', au2.hr_timestamp) = date_trunc('hour',
au1.hr_timestamp)
AND
au2.hr_timestamp < au1.hr_timestamp
WHERE au2.user_id is null;
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