Question

I have a TStringGrid with 10 columns. Adding 500 rows to it takes around 2 seconds. Is this normal performance?

It seems a bit slow to me.

I am getting the data from a database query. If I loop through the query but don’t write the results to the StringGrid, the process takes around 100ms, so it’s not the database that’s slowing things down.

Once the rows are added, the StringGrid performance is fine.

Here is the code I am using

Grid.RowCount := Query.RecordCount;
J := 0;

while not Query.EOF do
begin
    Grid.Cells[0,J]:=Query.FieldByName('Value1').AsString;
    Grid.Cells[1,J]:=Query.FieldByName('Value2').AsString;
    Grid.Cells[2,J]:=Query.FieldByName('Value3').AsString;
    // etc for other columns.
    Inc(J);
    Query.Next();
end;

The real code is actually a bit more complex (the table columns do not correspond exactly to the query columns) but that’s the basic idea

Answer 1

The solution was to add all values in a row at once, using the “Rows” property.

My code now looks like this:

Grid.RowCount := Query.RecordCount;
rowValues:=TStringList.Create;
J := 0;

while not Query.EOF do
begin
    rowValues[0]:=Query.FieldByName('Value1').AsString;
    rowValues[1]:=Query.FieldByName('Value2').AsString;
    rowValues[2]:=Query.FieldByName('Value3').AsString;
    // etc for other columns.
    Grid.Rows[J]:=rowValues;
    Inc(J);
    Query.Next();
end;

rowValues.Free; // for the OCD among us

This brought the time down from 2 seconds to about 50ms.