Re: [SQL] OFFSET impact on Performance???
| От | Ragnar Hafstað |
|---|---|
| Тема | Re: [SQL] OFFSET impact on Performance??? |
| Дата | |
| Msg-id | 1106248326.22416.22.camel@localhost.localdomain обсуждение исходный текст |
| Ответ на | Re: [SQL] OFFSET impact on Performance??? (Greg Stark <gsstark@mit.edu>) |
| Ответы |
Re: [SQL] OFFSET impact on Performance???
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| Список | pgsql-performance |
On Thu, 2005-01-20 at 11:59 -0500, Greg Stark wrote: > The best way to do pages for is not to use offset or cursors but to use an > index. This only works if you can enumerate all the sort orders the > application might be using and can have an index on each of them. > > To do this the query would look something like: > > SELECT * FROM tab WHERE col > ? ORDER BY col LIMIT 50 > > Then you take note of the last value used on a given page and if the user > selects "next" you pass that as the starting point for the next page. this will only work unchanged if the index is unique. imagine , for example if you have more than 50 rows with the same value of col. one way to fix this is to use ORDER BY col,oid gnari
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