Inequality Filters on a date and a number

Am trying to query my Google App Engine datastore [Python], which has a item_name, manufacturing_date and number_of_items_shipped. There are ~1.0 million records in the datastore and ever increasing.

The scenario: Get all the item_names which have been shipped more than x_items [user input] and manufactured after some_date [user input]. Basically, kind of an inventory check.

Effectively 2 inequalities on properties. But due to restrictions on queries in GAE, am not able to do this.

Searched SO for this issue. But, no luck till now. Did you come across this issue? If so, were you able to resolve this? Please let me know.

Also in Google I/O 2010, Next Gen Queries, Alfred Fuller mentioned that they are going to remove this restriction soon. Its been more than 8 months, but this restriction is in place even now. Unfortunately.

Appreciate if anyone can post an answer if they were able to circumvent this restriciton.

Thanks a lot.

Solution

Building on Sudhir's answer, I'd probably assign each record to a manufacture date "bucket", based on the granularity you care about. If your range of manufacturing dates is over a couple of years, use monthly buckets for example. If your range is just in the last year, weekly.

Now when you want to find records with > n sales and manufacturing date in a given range, do your query once per bucket in that range, and postfilter out the items you are not interested in.

For example (totally untested):

BUCKET_SIZE_DAYS = 10

def put(self):
    self.manufacture_bucket = int(self.manufacture_date.toordinal() / BUCKET_SIZE_DAYS)
    super(self.__class__, self).put()

def filter_date_after(self, date_start):
    first_bucket = int(date_start.toordinal() / BUCKET_SIZE_DAYS)
    last_bucket = int(datetime.datetime.today().toordinal() / BUCKET_SIZE_DAYS)

    for this_bucket in range(first_bucket, last_bucket+1):
        for found in self.filter("manufacture_bucket =", this_bucket):
            if found.manufacture_date >= date_start:
                yield found

You should be then able to use this like:

widgets.filter("sold >", 7).filter_date_after(datetime.datetime(2010,11,21))

Left as an exercise for the reader:

Making it play nicely with other filters added to the end
Multiple bucket sizes allowing you to always query ln(days in date range) buckets.