Question

I have 20 milliion rows in my table.I am trying to plot graph for timestamp using http://www.jqplot.com/tests/date-axes.php (date vs time) how will jquery handle so much of data to plot it. Two questions:

1.How can I construct an array from the below code:

line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];`

2.How can I improvize the code in this case:

def get_data(request):
 cdr = Cdr.objects.values_list('start_of_call',flat=True)
 context_instance=RequestContext(request, {})) 
 return render_to_response('cdr/get_data.html', context_instance=RequestContext(request, {'cdr':cdr}))

template:

<script class="code" type="text/javascript">
$(document).ready(function(){

{% for c in cdr %}
  {{ c|date:"d M Y"}}
{% endfor %}
 How to construct the below array line from for loop or using jquery methods
//var line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];

var plot1 = $.jqplot('chart1', [line1], {
title:'Default Date Axis',
axes:{xaxis:{renderer:$.jqplot.DateAxisRenderer}},
series:[{lineWidth:4, markerOptions:{style:'square'}}]
});
});
 </script>

EDIT

  line1=[['2008-09-30',4], ['2008-10-30',6], ['2008-11-30',5], ['2008-12-30',9], ['2009-01-30',8]];`

In the above line 4,6,5,9,8 are the hours

EDIT2

CDR values:

    [datetime.datetime(2012, 9, 13, 15, 54, 52, tzinfo=<UTC>), datetime.datetime(2012, 9, 22, 18, 24, 18, tzinfo=<UTC>), datetime.datetime(2012, 9, 6, 7, 42, 50, tzinfo=<UTC>), datetime.datetime(2012, 9, 7, 21, 27, 13, tzinfo=<UTC>), datetime.datetime(2012, 9, 3, 11, 57, 9, tzinfo=<UTC>), datetime.datetime(2012, 9, 1, 17, 23, 41, tzinfo=<UTC>), datetime.datetime(2012, 9, 15, 6, 14, 33, tzinfo=<UTC>), datetime.datetime(2012, 9, 4, 5, 36, 30, tzinfo=<UTC>), datetime.datetime(2012, 9, 17, 10, 45, 6, tzinfo=<UTC>), datetime.datetime(2012, 10, 1, 3, 1, 17, tzinfo=<UTC>), datetime.datetime(2012, 9, 27, 8, 36, 41, tzinfo=<UTC>), datetime.datetime(2012, 9, 30, 3, 12, 18, tzinfo=<UTC>), datetime.datetime(2012, 9, 18, 4, 8, 49, tzinfo=<UTC>), datetime.datetime(2012, 9, 2, 7, 21, tzinfo=<UTC>), datetime.datetime(2012, 9, 19, 16, 57, 34, tzinfo=<UTC>), datetime.datetime(2012, 9, 17, 17, 14, 49, tzinfo=<UTC>), datetime.datetime(2012, 9, 1, 22, 40, 33, tzinfo=<UTC>), datetime.datetime(2012, 9, 15, 1, 7, 39, tzinfo=<UTC>), datetime.datetime(2012, 9, 22, 17, 11, 45, tzinfo=<UTC>), datetime.datetime(2012, 9, 10, 3, 16, 21, tzinfo=<UTC>), '...(remaining elements truncated)...']

Answer 1

something like this:

from django.utils import simplejson

def get_data(request):
    cdr = [(x.strftime('%Y-%M-%D'), x.hour) for x in \
            Cdr.objects.values_list('start_of_call',flat=True)]
    return render_to_response('cdr/get_data.html',
                              {'cdr': simplejson.dumps(cdr)},
                              context_instance=RequestContext(request))

The format string in strftime might be a bit off – check it here: http://docs.python.org/2.7/library/datetime.html#strftime-strptime-behavior

by the way your view did some weird things with RequestContext – the above is the more usual style.

template:

line1 = jQuery.parseJSON({{ cdr }})

As for issues with sample size – there’s no clear answer – it’s going to depend on your network connection, your browser and machine. That siad 20M is very big – consider sampling the dataset to bring it down to a more manageable size – experimentation is going to be the best way.