using gnuplot to plot data from a file

Question

I am trying to plot some data using pgfplots, but the data are so extensive that the maximum capacity is reached. I get the error: TeX capacity exceeded, sorry [main memory size=3000000].

What can I do to work around that problem? I am thinking of gnuplot, but I can't seem to get the syntax right. So, I wanted to plot the data, which is in a file, using gnuplot. I tried the following:

\addplot gnuplot [raw gnuplot,id=test,only marks]{plot 'date.dat' using 0:1};

In the pgfplot manual I could only find information about using gnuplot, when using functions, but not for cases when the data are already in an external file. I constructed a mwe down low, where you can see how I usualy plot my graphs. That works fine unless the datafile is a lot bigger than the one you'll see below.

Thanks a lot for your help.

\documentclass{scrbook}

\usepackage{pgfplots}
\usepgfplotslibrary{dateplot}
\usepackage{tikz}
\usepackage{filecontents}

\begin{filecontents}{date.dat}
2012-01-01  1   3
2012-01-02  2   4
2012-01-03  2   5
\end{filecontents}

\begin{document}

\begin{figure}
    \begin{tikzpicture}
        \begin{axis}
            [
            width=0.9\textwidth,
            height=0.3\textheight,
            date coordinates in=x,
            unbounded coords=jump,
            xtick={2012-01-01,2012-01-02,2012-01-03},
            clip=false,
            ]
            \addplot [only marks,mark size=1pt,red]table [x index=0,y index=1] {date.dat};
            \addplot [only marks,mark size=1pt,green]table [x index=0,y index=2] {date.dat};
        \end{axis}
    \end{tikzpicture}
\end{figure}

\end{document}