CHeck this:
http://google-appengine.googlegroups.com/web/efficient_paging_using_key_instead_of_a_dedicated_unique_property.txt?gda=7FbhWXcAAACSStSWrftt07H4FK2Rtvurv5Qi9dmYyYZMEnTZCjCsYQQgER4RQV57mxjvIzAWBZmQ3TeCdbqm30Qz_AwgYlIpRbcWRj3jGGBm-fgbnPJIYc4-hXRRmo3Xgj6KgtSLBeZ45alvcyXc30EbEX-RNDZveV4duv6pDMGhhhZdjQlNAw
On 4月19日, 下午12时32分, Chris <chriss...@gmail.com> wrote:
> I have the model:
>
> class Record(db.Model):
> date = db.DateProperty()
>
> Over 1000 Record instances may contain the same date value. The
> instances are also not created in the order of their dates.
>
> I'm trying to query all instances whose date is within a given range.
> I need to be able to query sets larger than the default max of 1000.
>
> I was thinking of doing something like:
>
> Record.all().filter('date >', startDate).filter('date <', endDate)
>
> But this would limit me at most to the first 1000 records. How would I
> get the next 1000 records, maintaining the range query? I can't use
> the last date value from the previous query as the startDate for the
> next query, since there's no guarantee that the date value has
> changed. For example, I could have 2000 instances with the date
> 2008-1-1, so the first and second query sets have identical filter
> parameters.
>
> Intuitively, I could accomplish this by simply filtering on the
> previous key value (e.g. .filter('key >', lastKeyValue)).
> Unfortunately, App Engine currently prohibits filtering with
> inequality operators on more than one property.
>
> Am I correct in understanding that there's essentially no way to query
> all instances within a specific date range, due to this limitation?
>
> This issue keeps coming up for me, and has been a huge deal-breaker in
> a lot of potential projects I've been working on for App Engine. Any
> advice on how I could work around it would be appreciated.
>
> Chris
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