"Out of Memory" error when extracting many BLOB files from SQL Server database with Delphi program

I'm trying to extract a large number of files stored in a BLOB column in a SQL Server database. The files are being saved correctly to a directory, but after processing approximately 30,000 files, the program throws the error:

Out of Memory

I believe I've cleaned up all resources properly after each file, and I've also added fetch options to handle large datasets. Despite this, the memory usage keeps increasing until the program crashes.

Does anyone know what might be causing this issue or how I can better manage memory in this situation?

procedure TForm1.ExtractInvoicesFromBlobs(AMinInvNo, AMaxInvNo: Integer);
var
  PrintDate, FileName, BaseFolder, TargetFolder: string;
  FileStream: TFileStream;
  BlobStream: TStream;
  RecordCount: Integer;
begin
  // init
  RecordCount := 0;
  Memo1.Clear;

  // retrieve data from db
  FDQuery1.SQL.Clear;
  FDQuery1.SQL.Text := 'SELECT ID, PrintedFile, Filename, PrintDateTime ' +
                       'FROM InvoiceStorage ' +
                       'WHERE Filename BETWEEN :MinFilename AND :MaxFilename';
  FDQuery1.ParamByName('MinFilename').AsString := Format('%d.pdf', [AMinInvNo]);
  FDQuery1.ParamByName('MaxFilename').AsString := Format('%d.pdf', [AMaxInvNo]);
  FDQuery1.Open;

  // these 2 lines are to prevent "out of memory" after approximately 30,000 pdf
  FDQuery1.FetchOptions.Mode := fmAll;
  FDQuery1.FetchOptions.Unidirectional := True;

  while not FDQuery1.Eof do
  begin
    try
      PrintDate := Copy(FDQuery1.FieldByName('PrintDateTime').AsString, 1, 4);
      BaseFolder := IncludeTrailingPathDelimiter(Edit3.Text);
      TargetFolder := Format(BaseFolder + '%s', [PrintDate]);
      ForceDirectories(TargetFolder);
      BlobStream := FDQuery1.CreateBlobStream(FDQuery1.FieldByName('PrintedFile'), bmRead);
      try
        FileName := IncludeTrailingPathDelimiter(TargetFolder) + FDQuery1.FieldByName('Filename').AsString;
        FileStream := TFileStream.Create(FileName, fmCreate);
        try
          FileStream.CopyFrom(BlobStream, BlobStream.Size);
        finally
          FileStream.Free;
        end;
      finally
        BlobStream.Free;
        BlobStream := nil;
      end;

      // Each 1,000 files: log and provide some breathing air to the system
      Inc(RecordCount);
      if RecordCount mod 1000 = 0 then
      begin
        Memo1.Lines.Add(Format('%d files processed...', [RecordCount]));
        TrimMemo;
        Application.ProcessMessages;
        Sleep(100);
      end;
    except
      on E: Exception do
        Memo1.Lines.Add(Format('Error while processing record %d: %s', [RecordCount, E.Message]));
    end;
    FDQuery1.Next;
  end;
  FDQuery1.Close;
end;

You need to use:

  FDQuery1.FetchOptions.Unidirectional := True;

before calling:

  FDQuery1.Open;

Remove:

  FDQuery1.FetchOptions.Mode := fmAll;