Remember where you "left off".
Your "Next" button now says something like ?page=5&size=50
When you get there, you are doing something like SELECT ... ORDER BY ... LIMIT 250, 50
Make it say ?after_id=12345&size=50
and then do SELECT ... WHERE id > 12345 ORDER BY ... LIMIT 51
With 51, you get 3 things:
* the 50 items (or fewer) for the page
* a clue that there will be a "Next" page
* the id of the first item for that Next page
'Exercises for the reader':
* each of the next 5
* each of the previous 5
* go to last page
* go to first page
* Knowing whether to have those links or 'gray them out'.
A sample UI layout (you've probably seen web pages like this):
GoTo Page  ...   15   ... [last]
*  represents a link.
* You are currently (for this example) on page 15
* It is showing you only the Next/Prev 2 pages.
I have encountered multiple cases where a "crawler" (eg, search engine) brought a site to
its knees because of "pagination via OFFSET".
"Pagination via OFFSET" is Order(N) to fetch a page; Order(N*N) to scan the entire list.
The first page takes 1 unit of effort. The second takes 2; etc. By the time the entire
list has been paged through, about N*N/2 units of work have been done.
My technique is Order(1) for a page, Order(N) for a complete scan.
N is the number of pages. Some implementations have more than 10,000 pages. 10,000 *
10,000 = 100 million !
> -----Original Message-----
> From: Andy Wallace [mailto:awallace@stripped]
> Sent: Wednesday, September 05, 2012 2:05 PM
> To: mysql@stripped
> Subject: Re: Understanding Slow Query Log
> Ok, this raises a question for me - what's a better way to do
> On 9/5/12 2:02 PM, Rick James wrote:
> > * LIMIT 0, 50 -- are you doing "pagination" via OFFSET? Bad idea.
> Andy Wallace
> iHOUSEweb, Inc.
> (866) 645-7700 ext 219
> "Sometimes it pays to stay in bed on Monday, rather than spending the
> rest of the week debugging Monday's code."
> - Christopher Thompson
> MySQL General Mailing List
> For list archives: http://lists.mysql.com/mysql
> To unsubscribe: http://lists.mysql.com/mysql