Django: Limit SQL execution time

Question

I'm building an API for access to my underlying models, and I would like my users to be able to do some fancy things (like filter on columns with __ operators). The only problem is sometimes these can take a long time.

How can I limit a fetch to a certain amount of resources? Time, cpu-cycles, memory, etc.

My current code (if it helps) :

from django import http
from django.core import serializers
from django.core.paginator import Paginator, InvalidPage, EmptyPage
from django.core.exceptions import FieldError

from metaward import models

from django.db import models as django_models

mimetypes = {
    "json" : "application/json",
    "xml"  : "application/xml",
#    "yaml" : "text/yaml",
}
FIELDERROR = 1

class Error(django_models.Model) :
    code = django_models.IntegerField()
    msg = django_models.CharField()

def serialize(format, objects) :
    response = http.HttpResponse(mimetype=mimetypes[format])
    serialized = serializers.serialize(format, objects, stream=response)
    return response

def get(request, model) :
    args = dict()
    for k in request.GET :
        args[str(k)] = str(request.GET.get(k))

    format = args.pop("format", None)
    if format not in mimetypes.keys() :
        format = "xml"

    try :
        page = int(args.pop('page', '1'))
    except ValueError :
        page = 1

    try :
        result = model.objects.filter(**args)
    except FieldError, why :
        return serialize(format, [Error(code=FIELDERROR, msg=why)])

    paginator = Paginator(result, 100)

    try :
        paged = paginator.page(page)
    except (EmptyPage, InvalidPage) :
        paged = paginator.page(paginator.num_pages)

    return serialize(format, paged.object_list)

def award(request) :
    return get(request, models.Award)

def alias(request) :
    return get(request, models.Alias)

def user(request) :
    return get(request, models.User)

And the urls.py

urlpatterns += patterns('',
    url(r'^api/v2/award', api.award, name="api-award"),
    url(r'^api/v2/alias', api.alias, name="api-alias"),
    url(r'^api/v2/user', api.user, name="api-user"),
)