Thread: how to handle Pagination >

Hi,
I want to fetch records from the database and paginate in php script.
How this can be handled?

With Best Regards
Madhavan

On 10/15/2013 05:01 PM, jesusthefrog wrote:
> You will probably want to use OFFSET and LIMIT, which are the window
> size and page. Something like
>
> SELECT .. FROM ... WHERE ... ORDER BY (...) OFFSET y LIMIT x
>
> So say you want to get 100 records at a time. You would get page 1
> with OFFSET 0 LIMIT 100, then page 2 with OFFSET 100, OFFSET 200, and
> so on.

You will most certainly NOT want to use that technique.

Instead, try these links:

https://wiki.postgresql.org/wiki/File:Pagination_Done_the_PostgreSQL_Way.pdf

http://microjet.ath.cx/WebWiki/ResultPaginationWithPostgresql.html

https://coderwall.com/p/lkcaag

http://www.depesz.com/2007/08/29/better-results-paging-in-postgresql-82/
--
Vik

At 10:52am -0400 Tue, 15 Oct 2013, Madhavan wrote:
>> I want to fetch records from the database and paginate in php
>> script. How this can be handled?

At 11:01am -0400 Tue, 15 Oct 2013, Jesusthefrog wrote:
> You will probably want to use OFFSET and LIMIT, which are the window
> size and page. Something like
>
> SELECT .. FROM ... WHERE ... ORDER BY (...) OFFSET y LIMIT x
>
> So say you want to get 100 records at a time. You would get page 1
> with OFFSET 0 LIMIT 100, then page 2 with OFFSET 100, OFFSET 200, and
> so on.
>
> That's just off the top of my head. There may be another solution
> which will work better in your case, but lacking details, this is
> what I would recommend.

The common wisdom (of which I'm aware, anyway) is that the limits of
this approach are in the atomicity of the 2+ pages at which a user
looks.  For instance, if the user looks at page 1 (say, records 1-100),
then the SQL would look something like:

      SELECT ... ORDER BY ... OFFSET 0 LIMIT 100;

Now, while the user (user A) spends time reading the results, another
user or process updates the table, say by removing records 40-49 (10
total records removed).  Now, user A loads the next page of results,
which begins at offset 100:

      SELECT ... ORDER BY ... OFFSET 100 LIMIT 100;

The problem is that this is a new query, so offset 100 refers to what
/was/ record 110, instead of what the user probably wanted, which is now
OFFSET 90.

See this for a better explanation:

      https://coderwall.com/p/lkcaag

Then note that the Postgres community has "solved" this problem:


https://wiki.postgresql.org/wiki/File:Pagination_Done_the_PostgreSQL_Way.pdf

Cheers,

Kevin

At 12:54pm -0400 Tue, 15 Oct 2013, Vik Fearing wrote:
> On 10/15/2013 05:01 PM, jesusthefrog wrote:
>> You will probably want to use OFFSET and LIMIT, which are the
>> window size and page. Something like
>>
>> SELECT .. FROM ... WHERE ... ORDER BY (...) OFFSET y LIMIT x
>>
>> So say you want to get 100 records at a time. You would get page 1
>> with OFFSET 0 LIMIT 100, then page 2 with OFFSET 100, OFFSET 200,
>> and so on.
>
> You will most certainly NOT want to use that technique.
>
> Instead, try these links:

Doh!  My previous email was late!  Vik wins this round!  :-)

Kevin