Re: Two optimization questions
От | Mezei Zoltán |
---|---|
Тема | Re: Two optimization questions |
Дата | |
Msg-id | 4507051B.1050800@telefor.hu обсуждение исходный текст |
Ответ на | Re: Two optimization questions ("Aaron Bono" <postgresql@aranya.com>) |
Список | pgsql-sql |
Aaron Bono wrote: > You could split it into sub-queries but would that make the > performance better or worse? I guess it depends on how much data is > there, and what frequency you have ot the event_type's but indexing > the event_type column would help. This may be worth a try - use > EXPLAIN to see which is better. > Yep, I tought of that, but the solution with having is faster now. I think it is because about 30% of the rows are selected in the subquery now. Later we will have more records, and the subselect should select only about 1-2% of the rows. At that time, I think your solution will be faster. > Questions like this come up frequently and there are some nice solutions: > > See if this gives you some insight: > > select > '2006-01-15'::date + s.inc > from > generate_series(0, ('2006-02-20'::date - > '2006-01-15'::date)::integer) as s(inc) Sup, that's just what I needed. Thank you. Zizi
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