Ravi-
If you are having to create the connection to the database each time, this
is a strain on system resources and is slow and inefficient; but, if you are
using a pooled connection that remains open between calls then this is fast
and efficient.
If your connection is pooled, then I'd wager that you should probably just
make another SQL call to the database using ORDER BY and let the database do
the work. That's what it's made for.
Just my opinion.
> -----Original Message-----
> From: A mailing list for discussion about Sun Microsystem's Java Servlet
> API Technology. [mailto:[EMAIL PROTECTED]]On Behalf Of Ravi
> Shankar Jagarapu
> Sent: Thursday, July 19, 2001 5:28 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Sorting using servlets
>
>
> Richard,
>
> I would think the same way. The data I get is not
> large, so I could store it in a file.
>
> I haven't tested by seeing whether reading from a file
> or connecting from a database is faster.
>
> Did anyone implement this before and have any idea
> about performance issues talked about?
>
> Ravi.
> --- Richard Yee <[EMAIL PROTECTED]> wrote:
> > Ravi,
> > How much data are you talking about here? Using
> > either a file or the
> > session to store the data is not a very good idea.
> > Using a file limits the
> > scaleability and would be relatively slow.
> > Maintenance of the temporary
> > files also becomes an issue. Use of files is also
> > problematic if server
> > clusters are used b/c it ties the session to a
> > particular machine. Large
> > amounts of data should not be stored in the user's
> > session either b/c it
> > limits the scaleability again and eats up the
> > server's memory.
> >
> > For a large # of records, I'd recommend just
> > connecting to the database
> > again and use the database to sort for you using the
> > ORDER BY clause. The
> > database is highly optimized for this purpose. An
> > EJB is a great solution
> > if you can use them.
> >
> > Regards,
> >
> > Richard
> >
> > At 10:14 AM 7/19/01 -0700, you wrote:
> > >Kevin,
> > >
> > >Thanks a lot for gving me such useful pointers.
> > >Though aware of Lists and Comparators, I didn't
> > know
> > >TreeMaps.
> > >
> > >>From my original question of sorting, the data
> > needs
> > >to be stored somewhere, right either in a file
> > using
> > >TreeMaps or in the session.
> > >
> > >Performance wise which would be better?
> > >
> > >Thanks,
> > >Ravi.
> > >
> > >--- Kevin Baynes <[EMAIL PROTECTED]> wrote:
> > >> Ravi-
> > >>
> > >> You need to look at the Collections API for
> > storing
> > >> your data. This will
> > >> teach you about TreeMaps, Lists and Comparators:
> > >>
> > >>
> >
> >http://developer.java.sun.com/developer/onlineTraining/collection
> s/Collectio
> > >> n.html
> > >>
> >
> >http://developer.java.sun.com/developer/technicalArticles/Collect
> ions/Using/
> > >> index.html
> > >>
> > >> You will also need to understand Serialization
> > and
> > >> the Serializable
> > >> interface:
> > >>
> > >>
> >
> >http://java.sun.com/docs/books/tutorial/essential/io/serializing.html
> > >>
> >
> >http://java.sun.com/products/jdk/1.2/docs/guide/serialization/
> > >> be sure to look at the examples and FAQ in the
> > above
> > >> link.
> > >>
> > >> Kevin Baynes
> > >> SEAGULL Software
> > >>
> > >>
> > >>
> > >> > -----Original Message-----
> > >> > From: A mailing list for discussion about Sun
> > >> Microsystem's Java Servlet
> > >> > API Technology.
> > >> [mailto:[EMAIL PROTECTED]]On Behalf
> > Of
> > >> Ravi
> > >> > Shankar Jagarapu
> > >> > Sent: Wednesday, July 18, 2001 11:01 PM
> > >> > To: [EMAIL PROTECTED]
> > >> > Subject: Re: Sorting using servlets
> > >> >
> > >> >
> > >> > Hi Mark,
> > >> >
> > >> > It would be great if you could give me an
> > example
> > >> > code. I did not understand what you wrote? is
> > >> there
> > >> > any article where I could read about that?
> > >> >
> > >> > I don't know what is a TreeMap. Could you
> > >> enlighten
> > >> > me?
> > >> >
> > >> > Thanks,
> > >> > Ravi.
> > >> >
> > >> > --- Mark Galbreath <[EMAIL PROTECTED]> wrote:
> > >> > > Nah...that would not be efficient. Better to
> > do
> > >> it
> > >> > > on the server by sending
> > >> > > the data into a TreeMap (implements
> > SortedMap)
> > >> and
> > >> > > make it available to all
> > >> > > clients through a serialized download.
> > >> > >
> > >> > > Cheers!
> > >> > > Mark
> > >> > >
> > >> > > ----- Original Message -----
> > >> > > From: "Mike Peyvandi" <[EMAIL PROTECTED]>
> > >> > > Sent: Tuesday, July 17, 2001 11:39 PM
> > >> > >
> > >> > >
> > >> > > > Another option would be an applet in the
> > >> response
> > >> > > to take care of sorting
> > >> > > at
> > >> > > > the client side. This way you can omit
> > some
> > >> extra
> > >> > > calls to the server for
> > >> > > > sorting purpose.
> > >> > > >
> > >> > > > Mike
> > >> > > >
> > >> > > >
> > >> > > > -----Original Message-----
> > >> > > > From: Kevin Baynes
> > >> > > > Sent: Tuesday, July 17, 2001 2:43 PM
> > >> > > >
> > >> > > > Ravi-
> > >> > > >
> > >> > > > You could make the database call, save the
> > >> results
> > >> > > into a temporary
> > >> > > > structure, put it where you can access it
> > on
> > >> the
> > >> > > next call. You can do
> > >> > > this
> > >> > > > by either saving it to the Session, or by
> > >> > > serializing it to a file and
> > >> > > > accessing it by some key that you save to
> > the
> > >> > > Session.
> > >> > > >
> > >> > > > You could use Arrays, Vectors, Lists, or a
> > >> custom
> > >> > > built object.
> > >> > > >
> > >> > > > I suggest you use Lists and Comparators for
> > >> > > storage and sorting.
> > >> > > >
> > >> > > > Kevin Baynes
> > >> > > > Seagull Software
> > >> > > >
> > >> > > > > -----Original Message-----
> > >> > > > > From: Ravi Shankar Jagarapu
> > >> > > > > Sent: Tuesday, July 17, 2001 12:39 PM
> > >> > > > >
> > >> > > > > I am retrieving data from the database
> > with
> > >> > > several
> > >> > > > > fields, like for example first name, last
> > >> name,
> > >> > > > > join date, salary.
> > >> > > > >
> > >> > > > > This data is displayed by the servlet.
> > >> > > > > Now my requirement, is that, if anyone
> > >> clicks on
> > >> > > first
> > >> > > > > name, the data should now be displayed
> > >> sorted on
> > >> > > that
> > >> > > > > field and if on salary then sorted on
> > >> salary.
> > >> > > > >
> > >> > > > > I don't want to connect to the database
> > each
> > >> > > time and
> > >> > > > > retrieve the same information just to
> > sort
> > >> the
> > >> > > data
> > >> > > > > which is already available to me.
> > >> > > > >
> > >> > > > > Can anyone suggest a better method? Would
> > be
> >
> === message truncated ===
>
>
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