🚀 go-pugleaf

You may also reduce number of calls to MoveBy() or RecNo by implementing
cache for rows (and values of all fields) that are about to display using
TListView::OnDataHint() event. In OnData you just read from cache. It is
similar to way TDBGrid works and could significantly speedup displaying. I
remeber that I did this in one project and this helped.

//------------------------------------------
Regards,
Vassiliev V. V.
http://www.managed-vcl.com - using .Net objects in Delphi for Win32 +
ADO.Net
http://www.oledbdirect.com - The fastest way to access MS SQL Server,
MS Jet (Access) and Interbase (through OLEDB)

"Vic" <victor@espainformatica.com> �������/�������� � �������� ���������:
news:414191f5@newsgroups.borland.com...
> I'm trying to use bookmarks, First() and MoveBy(XX), but I only obtain a
> slowest scroll.
> Can you show me some example about how and in which listview's events i
must
> use the bookmarks and the other functions ?
>
> "Viatcheslav V. Vassiliev" <support@oledbdirect.com> escribi� en el
mensaje
> news:41417741$1@newsgroups.borland.com...
> > Client-side cursor caches all data in memory, so it is like copy
recordset
> > to memory. You may try to scroll recordset and cache bookmarks, and
> instead
> > of RecNo use Bookmark. Also calling First(), then MoveBy(XX) may
increase
> > speed because another mechanism is used.
> >
> > DBGrid caches some data for visible rows and this could speed up
> displaying
> > data.
> >
> > 40 000 records could occupy quite much memory (RAM in case of client
> cursor)
> > if there are many columns or there are BLOBs. If this is the problem,
you
> > may create temp Access db, copy data from SQL Server into this Access db
> > (with SELECT .. INTO from Access db) and use use data from this database
> > with server-side cursor (bookmarks are preffered over RecNo). This
should
> > work if your data will be up to ~1 GB.
> >
> > General recommendation is avoid using so large recordset with UI.
> >
> > //------------------------------------------
> > Regards,
> > Vassiliev V. V.
> > http://www.managed-vcl.com - using .Net objects in Delphi for Win32 +
> > ADO.Net
> > http://www.oledbdirect.com - The fastest way to access MS SQL Server,
> > MS Jet (Access) and Interbase (through OLEDB)
> >
> > "Vic" <victor@espainformatica.com> �������/�������� � ��������
���������:
> > news:4140ac2b@newsgroups.borland.com...
> > > > What is your DBMS?
> > > > > Info : I'm using builder 6 and sqlserver 2000 in windows xp sp1.
> > > SQL Server 2000 :)
> > >
> > > > What is cursor type (server or client)?
> > > Client.
> > >
> > > > Is db server on local computer or remote?
> > > db server is on a remote computer
> > >
> > > If you need more information ask me what you need?
> > >
> > > "Viatcheslav V. Vassiliev" <support@oledbdirect.com> escribi� en el
> > mensaje
> > > news:414095c6@newsgroups.borland.com...
> > > > What is your DBMS? What is cursor type (server or client)? Is db
> server
> > on
> > > > local computer or remote?
> > > >
> > > > //------------------------------------------
> > > > Regards,
> > > > Vassiliev V. V.
> > > > http://www.managed-vcl.com - using .Net objects in Delphi for Win32
+
> > > > ADO.Net
> > > > http://www.oledbdirect.com - The fastest way to access MS SQL
Server,
> > > > MS Jet (Access) and Interbase (through OLEDB)
> > > >
> > > > "Vic" <victor@espainformatica.com> �������/�������� � ��������
> > ���������:
> > > > news:414078e5@newsgroups.borland.com...
> > > > > I have a problem with the TADOQuery. In my project I need to read
> > > records
> > > > > ( about 40000 ) from some tables and show them in a list. For do
it,
> I
> > > use
> > > > a
> > > > > virtual TListview (OwnerData = true) and the ADOQuery with a SQL
> > > statement
> > > > > to read from database. The process for reading records from the
> > database
> > > > to
> > > > > the query is fast, it gets about 3 sec., and I use the event
OnData
> of
> > > the
> > > > > listview to show the records directly form the query.
> > > > > Here is the code :
> > > > >
> > > > > void __fastcall TForm1::ListView1Data(TObject *Sender, TListItem
> > *Item)
> > > > > {
> > > > >    ADOQuery->RecNo = Item->Index + 1;
> > > > >
> > > > >    for ( int i = 0; i < ListView1->Columns->Count; i++ )
> > > > >    {
> > > > >       if ( i == 0 )
> > > > >             Item->Caption =
ADOQuery->FieldByName("CODIGO")->Value;
> > > > >       else
> > > > >
> > > > > Item->SubItems->Add(ADOQuery->FieldByName("NOMBREFISCAL")->Value);
> > > > >    }
> > > > > }
> > > > >
> > > > > Before show the records directly from the query, I tried to copy
the
> > > query
> > > > > to my own list, and show the records from the list, but that
process
> > was
> > > > > very very very slow. Then I decide to avoid the 'QueryToMemory'
> > process.
> > > > >
> > > > > The problem that I have now is when I scroll the listview. While
at
> > the
> > > > top
> > > > > of the listiew the scrolling is fast, when I go to
> > > > > the bottom of it the scrolling is much slower.
> > > > >
> > > > > I think that the problem should be here :
> > > > >    ADOQuery->RecNo = Item->Index + 1;
> > > > > because if I comment this line, the scroll process returns to the
> > normal
> > > > > performance, but ofcourse I can't comment this line.
> > > > >
> > > > > How can I solve that problem ?
> > > > > Is it any other faster way to do what I need ?
> > > > >
> > > > > Thank you in advance.
> > > > >
> > > > > Info : I'm using builder 6 and sqlserver 2000 in windows xp sp1.
> > > > > --
> > > > > Victor
> > > > > ESPA Inform�tica.
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
>
>