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    <p>i found the performance problems with ADOExpress years ago:</p> <ul> <li><a href="http://groups.google.com/group/borland.public.delphi.database.ado/browse_thread/thread/c912b61b28472829" rel="nofollow">ADO vs ADOExpress time trials. Not good for ADOExpress</a> (6/7/2005)</li> <li><a href="http://groups.google.com/group/borland.public.delphi.database.ado/browse_thread/thread/5932d926801a407f/720a59662558ad05" rel="nofollow">ADO vs ADO Express Time Trials (redux)</a> (12/30/2007)</li> </ul> <blockquote> <p><strong>Note:</strong> Before ADO became a standard part of Delphi, Borland was selling it as an addon called <strong>ADOExpress</strong>. It was simply object wrappers around Microsoft's ActiveX Data Objects (ADO) COM objects.</p> </blockquote> <p>i had tested three scenarios</p> <ul> <li>using ADO directly (i.e. Microsoft's COM objects directly)</li> <li>using ADOExpress (Borland's object wrappers around ADO)</li> <li>specifying <code>.DisableControls</code> on the <code>TADOQuery</code> before calling <code>Open</code></li> </ul> <p>i discovered</p> <ul> <li>use <code>Query.DisableControls</code> to make each call <code>.Next</code> 50x faster</li> <li>use <code>Query.Recordset.Fields.Items['columnName'].Value</code> rather than <code>Query.FieldByName('columnName')</code> to make each value lookup 2.7x faster</li> <li><p>using <code>TADODataSet</code> (verses <code>TADOQuery</code>) makes no difference</p> <pre><code> Loop Results Get Values ADOExpress: 28.0s 46.6s ADOExpress w/DisableControls: 0.5s 17.0s ADO (direct use of interfaces): 0.2s 4.7s </code></pre></li> </ul> <p><strong>Note</strong>: These values are for looping 20,881 rows, and looking up the values of 21 columns.</p> <p><strong>Baseline Bad Code:</strong></p> <pre><code>var qry: TADOQuery; begin qry := TADOQuery.Create(nil); try qry.SQL.Add(CommandText); qry.Open; while not qry.EOF do begin ... qry.Next; end; </code></pre> <p><strong>Use DisableControls to make looping 5000% faster</strong>:</p> <pre><code>var qry: TADOQuery; begin qry := TADOQuery.Create(nil); try qry.DisableControls; qry.SQL.Add(CommandText); qry.Open; while not qry.EOF do begin ... qry.Next; end; </code></pre> <p><strong>Use Fields collection to make value lookups 270% faster</strong>:</p> <pre><code>var qry: TADOQuery; begin qry := TADOQuery.Create(nil); try qry.DisableControls; qry.SQL.Add(CommandText); qry.Open; while not qry.EOF do begin value1 := VarAsString(qry.Recordset.Fields['FieldOne'].Value); value2 := VarAsInt(qry.Recordset.Fields['FieldTwo'].Value); value3 := VarAsInt64(qry.Recordset.Fields['FieldTwo'].Value); value4 := VarAsFloat(qry.Recordset.Fields['FieldThree'].Value); value5 := VarAsWideString(qry.Recordset.Fields['FieldFour'].Value); ... value56 := VarAsMoney(qry.Recordset.Fields['FieldFive'].Value); qry.Next; end; </code></pre> <hr> <p>Since it is a common enough problem, we created a helper method to solve the issue:</p> <pre><code>class function TADOHelper.Execute(const Connection: TADOConnection; const CommandText: WideString): TADOQuery; var rs: _Recordset; query: TADOQuery; nRecords: OleVariant; begin Query := TADOQuery.Create(nil); Query.DisableControls; //speeds up Query.Next by a magnitude Query.Connection := Connection; Query.SQL.Text := CommandText; try Query.Open(); except on E:Exception do begin Query.Free; raise; end; end; Result := Query; end; </code></pre>
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    1. USIan Boyd
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    1. COWhen do you re-enable the controls? I always use a try ... finally block when disabling the controls to ensure that the controls (the datagrid) is re-enabled whatever happens.
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      1. USNo'am Newman
    2. CO@No'amNewman We never, never, ever, use databound controls. Ever. Doing everything yourself is so much faster and easier.
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    3. COI'd have to disagree with you. I've written a few non-bound dialogs; some were easy to write but some were very hard, thus increasing the chances of making a mistake or leaving something out.
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