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Thread View: borland.public.cppbuilder.database.multi-tier
2 messages
2 total messages Started by peterayre Mon, 02 Aug 1999 00:00
Making Midas useful
#1692
Author: peterayre
Date: Mon, 02 Aug 1999 00:00
40 lines
2171 bytes
Please feel free to correct me or point out any mistakes in what I am about
to post.
I have not been using the Midas stuff until now and admit that I may be
missing something.

I have a multi-user system around 30 on our larger set-up.
This is attached to SQL Server using ODBC.

These machines are all querying away in a time critical application and
return data that is so similar that only filters would be required to
differentiate between any two set-ups.

currently this means that from 30 different sources a single query comes in
about twice a second.
This is a considerable load for a complex query on a large and busy table.

I had an Idea and thought that if I use the Midas components then I can make
this query once and then distribute it to many machines.
This seemed like a fine use of the multi tiered functions.

however a little checking shows me that when I try this I am not simply
returning the results of a single query to whichever applications request
them.  I am re-querying every time.  Using SQL Trace shows me the same query
hitting the server very time I open a new Client or refresh the view in an
existing client.

I want to make Midas work for me but if this is the normal behaviour then
what is the point.  I cannot see that it makes any difference if I query
directly from 30 points or get a single point to query for me 30 times.
I would be better setting up a temporary paradox table on a single machine.

It may be that I could loose the ODBC connection under this regime but on an
NT  based system I cannot see any gain.

As I said at the top I could be missing the point or just plain wrong but
PLEASE could someone enlighten me here.

Thanks

Peter
Re: Making Midas useful
#1699
Author: Michael A. Feinstein
Date: Fri, 06 Aug 1999 00:00
51 lines
2810 bytes
That is the default behavior.
To correct it , design you own TDataset descendant which would store
results in memory and write them back only when needed.
That is what I did and it proved to be successful.
The only drawback is that you do not see changes done by others to the
database (only by the application using your dataset).

e-mail me if you want more details.

peterayre@enterprise.net wrote:
> 
> Please feel free to correct me or point out any mistakes in what I am about
> to post.
> I have not been using the Midas stuff until now and admit that I may be
> missing something.
> 
> I have a multi-user system around 30 on our larger set-up.
> This is attached to SQL Server using ODBC.
> 
> These machines are all querying away in a time critical application and
> return data that is so similar that only filters would be required to
> differentiate between any two set-ups.
> 
> currently this means that from 30 different sources a single query comes in
> about twice a second.
> This is a considerable load for a complex query on a large and busy table.
> 
> I had an Idea and thought that if I use the Midas components then I can make
> this query once and then distribute it to many machines.
> This seemed like a fine use of the multi tiered functions.
> 
> however a little checking shows me that when I try this I am not simply
> returning the results of a single query to whichever applications request
> them.  I am re-querying every time.  Using SQL Trace shows me the same query
> hitting the server very time I open a new Client or refresh the view in an
> existing client.
> 
> I want to make Midas work for me but if this is the normal behaviour then
> what is the point.  I cannot see that it makes any difference if I query
> directly from 30 points or get a single point to query for me 30 times.
> I would be better setting up a temporary paradox table on a single machine.
> 
> It may be that I could loose the ODBC connection under this regime but on an
> NT  based system I cannot see any gain.
> 
> As I said at the top I could be missing the point or just plain wrong but
> PLEASE could someone enlighten me here.
> 
> Thanks
> 
> Peter
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