sybperl-l Archive

From: "ye, wei" <yw at alabanza dot net>
Subject: Re: Moving to a specific row
Date: Aug 31 2000 6:09PM

Michael Peppler wrote:

> Jeff Greif writes:
>  > I wrote this thing (groaning all the while) because the guy doing the web
>  > pages complained about how slow it was to throw away many thousands of rows
>  > to get at a page of 100 in the middle of a long result set, when the user
>  > clicked Next.  From a forms-based app, I guess you'd use some kind of browse
>  > cursor, but the HTTP environment in this case prevented holding the cursor
>  > across multiple web pages.  Because there was a user interaction to get each
>  > page, efficiency was not a huge concern (at least until hundreds of users
>  > start doing it simultaneously).  There's an index on the ordering field, so
>  > the basic queries are pretty efficient.  I'm not sure of the FETCH RELATIVE
>  > @offset from the cursor though -- even with a server-side cursor it must be
>  > pretty bad.
>
> Well...
>
> The correct way to do this in a set-based envionment is to use the
> unique primary key in the where clause to get the next X rows of a
> request.
>
> So assuming you have an identity column as the primary key, you simply
> remember the last value retrieved for the current page, and when the
> user hits "next" you do a request where the primary key > this value.

But in web page, usually the grid need to be shown sorted by different columns,
sometimes is by the primary key, sometimes not, so where the primary key > this
value
doesn't work.


>
>
> Pretty straightforward, and fast.
>
> Michael
>
>  > ----- Original Message -----
>  > From: "Michael Peppler" 
>  > To: "SybPerl Discussion List" 
>  > Sent: Thursday, August 31, 2000 9:38 AM
>  > Subject: Re: Moving to a specific row
>  >
>  >
>  > >
>  >   > brevity>
>  > >
>  > > Interesting.
>  > >
>  > > What does the showplan look like for such a request? (ie - is it
>  > efficient?)
>  > >
>  > > (and no, Sybase does not support this syntax)
>  >
>
> --
> Michael Peppler         -||-  Data Migrations Inc.
> mpeppler@peppler.org    -||-  http://www.mbay.net/~mpeppler
> Int. Sybase User Group  -||-  http://www.isug.com
> Sybase on Linux mailing list: ase-linux-list@isug.com

--

Sincerely,

Wei Ye