Re: Accessing a paradox table from a C# application...
- From: Michael Israel <mike@xxxxxxxx>
- Date: Thu, 08 Mar 2007 17:45:46 -0500
Just a guess but the problem is probably the indexes. PX is the file extension for the primary index or key. You have a compound key which can be a very large file. If you can you may want to add another field, an meaningless integer and use that as a the key. You can add secondary indexes where appropriate to enhance query performance. I would get a copy of Paradox (not expensive) and play around with restructuring the table and indexes and see what happens to query speed. Of course you can do all this with SQL, but a visual interactive approach by using Paradox may speed up your research.
Another possibility is the design of your network. There are several threads on the optimal way to set up a network. Check out thedbcommunity.com.
If you are using a client server system, you get better performance if the queries are run remotely (on the server). There is an option on Paradox as to where the queries are run. Give us a few more details about your network, what machines you are using and we can give you more help.
Hi everyone,.
First off, I am very new to using Paradox tables, so I am stumped as
to how I should go about addressing these problems.
Anyway, I have a C# application that needs to access a Paradox
database over a network (through an ODBC connection). I have
successfully been able to do this in the past, but when I tried to
deploy a change this morning, the performance was intolerable and even
crashed my application. At first, I thought that I simply couldn't
connect, but it turns out that the queries are not performing well.
For example, if I run the following query:
SELECT TOP 1 * FROM ModelSer
or even:
SELECT TOP 1000 * FROM ModelSer
the query runs fairly well (the latter is slower, obviously).
Now, the table is (supposed) to be set to have the model, serial, and
timestamp set as the primary key. This would lead me to expect that
if I try this query:
SELECT TOP 1 * FROM ModelSer ORDER BY Timestamp
...that it would run fairly quickly. However, that wasn't the case.
If I used a test database locally, it took me 2 minutes to get a
response. At first, I noticed that I didn't have BDE installed. I
installed it and noticed no performance difference. However, if I
delete the .PX file corresponding to the table, the performance is
much better. When I try to restructure it with the primary keys, the
performance sucks again.
I have doing this kind of thing for about 6 months, but I can't quite
get a handle on what is going on. Any advice would be greatly
appreciated.
Sincerely,
Jason Pell
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