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ADO slower than ODBC?

Posted on 2003-02-19
Medium Priority
Last Modified: 2013-11-23

In my Delphi 6 app, I am accessing a table on a MS SQL server with a little over 1 million records (Stock transactions). When I access it with ADO (tAdoQuery) with Cursorlocation = clUseClient it takes forever to open the dataset, and I need to use clUseClient in order to browse the dataset.

If I access the table through an ODBC datasource using TQuery it is a least 10 times faster to open the table and I can still browse the dataset.

I want to use ADO because it is easier to distribute, but how do I speed it up?

Thanks in advance
Question by:Landlyst
LVL 22

Accepted Solution

Mohammed Nasman earned 300 total points
ID: 7986053
  In much cases ADO is faster than ODBC, but the way you are using it will make the different in performace

  for example, you are using Cursorlocation = clUseClient, this mean that all the data will cached to the client, so this will take very long time with big tables, you should use where clause to return the records needed but not all the table

  also try to make the cursorlocation to be on server

  but always try to return specific records, not all the record

Best regards
Mohammed Nasman

Expert Comment

ID: 7986329

With ADO be carefully with connections. They are very slow on opening… If you make often close/open connection this will hit your performance. Open connection on start of your application and close it on exit.
And of course if your SELECT return millions of records and you use client cursor and your database is over network you must wait from minutes to hours for transferring all records over network to your client machine.


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ID: 9317170
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