Solved

OnFilterRecord and DBGrid?

Posted on 2002-06-12
11
694 Views
Last Modified: 2010-04-04
Hello, Everyone.

Im using the OnFilterRecord Event on a Paradox Table. Has anyone noticed even though if Filtered=false for the Table, the DBGrid scrolls slower? If I take off the OnFilterRecod event from code,it will go back to normal fast scrolling speed.

Its just weird, when Filtered is set to false it deosn't even goto any line in that event. So why does it become slow? The scrolling is even faster when Filter=true.


So go figure........it should be the other way around. Filtering should make things slower ;-)

Any suggestions are very welcome.

Thanks very much.

P.S
Im using a Table with about 30,000 records.And a Intel P3 1gz, with 256mb ram , and gb's of free disk space. The key is using a very large Table.

If you would like to test , try using a very large
Table . Set the Filtered property to false during design time, and add some commented lines to the OnFilterRecord Event(no real code is needed there , its just to make the event exist) . Now compile and run , you should have the same results.

 


0
Comment
Question by:superpower
11 Comments
 
LVL 27

Expert Comment

by:kretzschmar
Comment Utility
? weird ... listening
0
 
LVL 3

Expert Comment

by:marcoszorrilla
Comment Utility
Try this to avoid evaluation

Table1.OnFilterRecord := nil;

Best Regards.
Marcos.
0
 

Author Comment

by:superpower
Comment Utility
Hello,

No , I never get to this situation.

Table1.OnFilterRecord := nil;

Any other ideas?


BTW, it isnt as slow if I use a smaller Table. If you would like to test , try using a fairly large Table (more than 1000 records at least), set the Filtered property to false during design time, and only add code the OnFilterRecord Event . Now compile and run , you should have the same results.


Thanks.
0
 
LVL 27

Expert Comment

by:kretzschmar
Comment Utility
>you should have the same results
no, i have no difference (maybe my workstation is too fast)
0
 

Author Comment

by:superpower
Comment Utility
P.S

On the other hand, for tests try to use a Table with close enough records to 30,000 just as Im testing with :-)

If you dont have one, you experts know how to make one through a loop .
0
Free Trending Threat Insights Every Day

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

 
LVL 44

Expert Comment

by:CrazyOne
Comment Utility
Well I just tested with 30,000 records with and without an OnFilterRecord on a Paradox table and there appeared to be no difference in the srolling speed.

PII 450 384MB's RAM Win2000


The Crazy One
0
 

Author Comment

by:superpower
Comment Utility
Hello,

Here is the code I used,just to better illustrate.

unit cfilter;
   {Delphi3 Pro, also tried D5}
interface

uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
 Grids, DBGrids, Db, DBTables;

type
 TForm1 = class(TForm)
   Table1: TTable;

{40,000 record table(about 30field Table), Filtered Property is set to false , and Active is set to true during design time}

{same table structure with 8,000 records isnt so harshly
effected}

   DataSource1: TDataSource;
   DBGrid1: TDBGrid;
   procedure Table1FilterRecord(DataSet: TDataSet; var Accept: Boolean);
 private
   { Private declarations }
 public
   { Public declarations }
 end;

var
 Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Table1FilterRecord(DataSet: TDataSet;
 var Accept: Boolean);
begin

{testing lines}
{take comments out and watch how fast the scrolling speed becomes}

end;

end.
0
 

Author Comment

by:superpower
Comment Utility
P.S

Problem solved by myself just before I ran out of hope. This was one that really got me stuck.

I found a work around to this bug(It maybe so, or not) , becuase of all the code samples for OnFilterRecord in books, websites that Ive looked at ,had no such mention to do this.

On the OnShow event of the Form I just use

Table1.OnFilterRecord:=nil;

It seems Delphi doesn't like that event to be linked , when Filtered=false and some code exists in that event. So I unlink it. And call it back when I want the filtering to start.

Table1.OnFilterRecord := Table1FilterRecord;
Table1.Filtered=true;

But this was a rather tricky one. Becuase anyone trying the code on even a 10,000 record Table wouldnt even seen any difference. It had to be a 30k or 40k record Table with 30fields , in my case.


So do I get those points :-)
0
 
LVL 27

Expert Comment

by:kretzschmar
Comment Utility
really curious, because i could not reproduce

glad you had it solved yourself

ask at community-support for keep this q
into paq and refunds your points

meikl ;-)
0
 

Author Comment

by:superpower
Comment Utility
Thank everyon for trying to help anyway. Still appreciated.

meikl,

But I have one question coming up that maybe you can answer. :-) So il recycle these pionts I get back.
0
 
LVL 1

Accepted Solution

by:
Moondancer earned 0 total points
Comment Utility
Thanks all.  200 points refunded, item moved to our PAQ at zero points and closed.
Moondancer - EE Moderator
0

Featured Post

Free Trending Threat Insights Every Day

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

Join & Write a Comment

Suggested Solutions

Objective: - This article will help user in how to convert their numeric value become words. How to use 1. You can copy this code in your Unit as function 2. than you can perform your function by type this code The Code   (CODE) The Im…
Have you ever had your Delphi form/application just hanging while waiting for data to load? This is the article to read if you want to learn some things about adding threads for data loading in the background. First, I'll setup a general applica…
Polish reports in Access so they look terrific. Take yourself to another level. Equations, Back Color, Alternate Back Color. Write easy VBA Code. Tighten space to use less pages. Launch report from a menu, considering criteria only when it is filled…
This video shows how to remove a single email address from the Outlook 2010 Auto Suggestion memory. NOTE: For Outlook 2016 and 2013 perform the exact same steps. Open a new email: Click the New email button in Outlook. Start typing the address: …

744 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

12 Experts available now in Live!

Get 1:1 Help Now