Re: Takes too long to fetch the data from database
| От | soni de |
|---|---|
| Тема | Re: Takes too long to fetch the data from database |
| Дата | |
| Msg-id | 9f2e40a90604202142x5adbe6f0r7a993f8319619cc7@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Takes too long to fetch the data from database ("Merlin Moncure" <mmoncure@gmail.com>) |
| Ответы |
Re: Takes too long to fetch the data from database
Re: Takes too long to fetch the data from database Re: Takes too long to fetch the data from database |
| Список | pgsql-performance |
I don't want to query exactly 81900 rows into set. I just want to fetch 50 or 100 rows at a time in a decreasing order of stime.(i.e 50 or 100 rows starting from last to end).
if we fetched sequentially, there is also problem in fetching all the records (select * from wan where kname='pluto' order by stime) it is taking more than 4~5 minutes. tried it on same table having more than 326054 records.
On 4/20/06, Merlin Moncure <mmoncure@gmail.com> wrote:
> SELECT * FROM wan ORDER BY stime LIMIT 50 OFFSET 81900;
you need to try and solve the problem without using 'offset'. you could do:
BEGIN;
DECLARE crs cursor FOR SELECT * FROM wan ORDER BY stime;
FETCH ABSOLUTE 81900 in crs;
FETCH 49 in crs;
CLOSE crs;
COMMIT;
this may be a bit faster but will not solve the fundamental problem.
the more interesting question is why you want to query exactly 81900
rows into a set. This type of thinking will always get you into
trouble, absolute positioning will not really work in a true sql
sense. if you are browsing a table sequentially, there are much
better methods.
merlin
В списке pgsql-performance по дате отправления: