Re: [HACKERS] What about LIMIT in SELECT ? - Mailing list pgsql-hackers

What is wrong with the already implemented FETCH command?


On Tue, 13 Oct 1998, Terry Mackintosh wrote:

> Hi, my 2 cents...
>
> I agree completely, LIMIT would be VERY usefull in web based apps, which
> is all I run.  It does not matter to me if it is not part of a formal
> standard.  The idea is so common that it is a defacto standard.
>
> I would not expect it for this release, but could it get put on the TODO
> list for next time?  I am even willing to work at an apprentise level on
> this with a more expeireanced person that knows this stuff.
>
> A note on implimentation:
> I *used to* :) work with VFP on NT's :(
> And the way VFP did LIMIT, it would only return the number of rows asked
> for, BUT it still did the WHOLE search!
> So on a larger table, which we had (property tax database for the county),
> if some one put in too vague a query, it would try to collect ALL of the
> rows as the initial result set, then give you the first x rows of that.
>
> This did save on pushing mass amounts of data out to the browser, but it
> would have been even better if it could have simply aborted the select
> after having found x rows.
>
> Also, it did not have the concept of an offset, so one could not select
> 100 rows, starting 200 rows in, which would be REALLY usefull for "paging"
> through data.  I do not know if mySQL or any other has such a concept
> either, but it would be nice.
>
> So a properly implemented "LIMIT" could:
> 1.  Save pushing mass amounts of data across the web, that no one wants
> any way.
> 2.  Stop vague queries from bogging down the server.
> (On very larg tables this could be critical!)
> 3.  Enable "Paging" of data. (easyer then now (app. level))
> 4.  Would be a very nice feather in PostgreSQL's cap that could make it
> even more attractive to those looking at all sorts of databases out there.
>
> Have a great day.
>
> On Tue, 13 Oct 1998, Oleg Bartunov wrote:
>
> > Hi,
> >
> > I took a look at mysql and was very impressed with   possibility
> > to limit number of rows returned from select. This is very useful
> > feature for Web applications when user need to browse results of
> > selection page by page. In my application I have to do full
> > select every time user press button [Next] and show requested page
> > using perl. This works more or less ok for several thousands rows but
> > totally unusable for large selections. But now I'm about to work
> > with big database and I don't know how I'll stay with postgres :-)
> > It'll just doesn't work if customer will wait several minutes just browse
> > next page. Mysql lacks some useful features postgres has
> > (subselects, transaction ..) but for most Web applications I need
> > just select :-) I dont' know how LIMIT is implemented in Mysql and
> > I know it's not in SQL92 standart, but this makes Mysql very popular.
> >
> > Is it difficult to implement this feature in postgres ?
> >
> >     Regards,
> >
> >         Oleg
> >
> >
> > _____________________________________________________________
> > Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
> > Sternberg Astronomical Institute, Moscow University (Russia)
> > Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
> > phone: +007(095)939-16-83, +007(095)939-23-83
> >
> >
>
> Terry Mackintosh <terry@terrym.com>          http://www.terrym.com
> sysadmin/owner  Please! No MIME encoded or HTML mail, unless needed.
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Marc G. Fournier                               scrappy@hub.org
Systems Administrator @ hub.org
scrappy@{postgresql|isc}.org                       ICQ#7615664