Board index » delphi » ClientDataSet question

2004-11-27 03:34:16 AM
delphi20
Hi,
I'm developing a muiti-database application that supports ADO and IBX, and
I'm using like this:
(TADOQuery or TIBQuery) -->TProvider -->TClientDataSet
I connect the TProvider to TADOQuery or TIBQuery depending on a parameter,
where it is specified what database I will use (Interbase or SQLServer).
The problem is when I am selecting a large amount of records, 50000 and over,
for instance, it takes almost 2 minuts to open. Why it takes so long? Is
this the better way for building muiti-database applications? If it is not,
what would be?
Thanks for any help.
 

Jzlio Cesar writes:
caching them. Why so many records ?
--
Rob Schieck
TeamB
 

Hi,
Here goes:
1. In just one case I need to cache them all, because I generate a binary file using the ClientDataSet so that I can use the records from this file in another application that just make consults :)
2. I use so many records because I record all the records from a products table in this file. This file is used at a point-of-sale supermarket application that cannot depends on the server. If something happens to the server, the supermarket cannot stop selling :)
3. Is there a way to work like if I were using the TIBQuery or TADOQuery, were I can navegate through the records using a ClientDataSet and a Provider without caching them?
4. I use ClientDataSet and a Provider to make easier work with multi-databases, because I just need to connect the Provider at the specific query (TIBQuery or TADOQuery)! I there a better way to build multi-database appplications?
Thanks!
"Robert Schieck (TeamB)" <>writes:

If you are writing the records to an external file why not bring the
records to the client in small batchs and write the records out as they
are received? Than you will not need to cache the records in the
client. For an example see
bdn.borland.com/article/0,1410,25982,00.html
--
Bill (TeamB)
TeamB cannot answer questions received via email
 

Is your clientdatasets fetch on demand property set to true ?
--
Rob Schieck
TeamB
 

Yes, its by default.
<Robert Schieck (TeamB)>escreveu na mensagem

Ok, about the file I understood.
Now if you can explain me these two points, I will be very thankful.
First:
Is there a way to work with ClientDataSet were I can navegate through the
records without caching them?
Second:
Why selecting all the 50000 records using TADOQuery and a ClientDataSet
takes much longer (very very much longer!) than selecting the same records
using TIBQuery and a ClientDataSet?
Thanks once more!
"Bill Todd" <XXXX@XXXXX.COM>escreveu na mensagem

Jzlio Cesar writes:
true, set PacketRecords to some number, then call GetNextPacket,
process the records, call EmptyDataSet, then call GetNextPacket etc.
Are you using a unidirectional cursor with IBX?
 

I would expect IBX with Unidirectional=True + CDS to be faster than
dbExpress, however, I have never done any precise timings.
--
Bill (TeamB)
TeamB cannot answer questions received via email
Jzlio Cesar writes:

Sorry, I didn't pay attention on the cursor. Now its running better.
I made a test with DBX and it is faster then both. I will think about using DBX
for SQL Server and for Interbase.
Thanks a lot! :)
"Bill Todd" <XXXX@XXXXX.COM>escreveu na mensagem

Hi all,
I have a Delphi 6 stand alone application that I am planning on
redeveloping as a client/server app.
I am thinking of running the Firebird server, IBExpress,
with each of my client apps utilising ClientDataSets (CDS) to
manipulate clientside data, etc,.
I was considering connectin MS Access to my CDS as my client
side "briefcase", then applying updates back to the server once
my user had shut down the application (via a secondary system
tray application).
Is this the correct use of the CDS with the briefcase model?
The reason that I thought of using something like Access is that
when my client app disconnects from the network (ie laptop users)
they may well need to take up to 10,000 customer records with
them to work with in the "briefcase" model.
From my readings on the CDS it only seems useful if you want to
store a handful of records in a local XML file, rather than many
thousands?
Is this right? Am I just getting it all wrong here?
Many thanks,
jason.