I have a model with over 1000 records and I want to select the top N
records on field A that satisfy conditions on field B. (For example
the youngest N records with a certain name.)
My concern is if I only filter on field B and order in code
afterwards, then I will miss some records not in the top 1000.
I was hoping to create an index so that the results are always ordered
by field A, but that doesn't seem to be possible.
Ideas?
I believe you can create an index that sorts by youngest, then by name, and
you should be good. Assuming your "youngest" field is called "createdDate".
If I understand what I just typed, that will create an index on the MyModel
entity, ordering first by createdDate ascending then by A ascending. You
could, I believe, then do the following:
On Thu, Oct 29, 2009 at 6:53 PM, Baron <richar...@gmail.com> wrote:
> Hello,
> I have a model with over 1000 records and I want to select the top N
> records on field A that satisfy conditions on field B. (For example
> the youngest N records with a certain name.)
> My concern is if I only filter on field B and order in code
> afterwards, then I will miss some records not in the top 1000.
> I was hoping to create an index so that the results are always ordered
> by field A, but that doesn't seem to be possible.
> Ideas?
In my example I left out the sorts by A ascending because I later realised
it may not be necessary... I believe, however, that my index *does* sort by
createdDate ascending... I haven't written one in a long, long time, so my
apologies. ;)
On Thu, Oct 29, 2009 at 7:01 PM, ryan baldwin <ryanbald...@gmail.com> wrote:
> I believe you can create an index that sorts by youngest, then by name, and
> you should be good. Assuming your "youngest" field is called "createdDate".
> If I understand what I just typed, that will create an index on the MyModel
> entity, ordering first by createdDate ascending then by A ascending. You
> could, I believe, then do the following:
> That being said, I'm not sure if DataStore actually guarantees the order of
> results... I assume so...?
> - ryan.
> On Thu, Oct 29, 2009 at 6:53 PM, Baron <richar...@gmail.com> wrote:
>> Hello,
>> I have a model with over 1000 records and I want to select the top N
>> records on field A that satisfy conditions on field B. (For example
>> the youngest N records with a certain name.)
>> My concern is if I only filter on field B and order in code
>> afterwards, then I will miss some records not in the top 1000.
>> I was hoping to create an index so that the results are always ordered
>> by field A, but that doesn't seem to be possible.
>> Ideas?
I found that if I used my query a few times on the development server
then your above code snippet was automatically inserted in my
index.yaml - neat! (not app.yaml)
Then when I uploaded to Google App Engine I got errors for a few
minutes while the index was building, but eventually it worked.
On Oct 30, 12:02 pm, ryan baldwin <ryanbald...@gmail.com> wrote:
> In my example I left out the sorts by A ascending because I later realised
> it may not be necessary... I believe, however, that my index *does* sort by
> createdDate ascending... I haven't written one in a long, long time, so my
> apologies. ;)
> - ryan.
> On Thu, Oct 29, 2009 at 7:01 PM, ryan baldwin <ryanbald...@gmail.com> wrote:
> > I believe you can create an index that sorts by youngest, then by name, and
> > you should be good. Assuming your "youngest" field is called "createdDate".
> > If I understand what I just typed, that will create an index on the MyModel
> > entity, ordering first by createdDate ascending then by A ascending. You
> > could, I believe, then do the following:
> > That being said, I'm not sure if DataStore actually guarantees the order of
> > results... I assume so...?
> > - ryan.
> > On Thu, Oct 29, 2009 at 6:53 PM, Baron <richar...@gmail.com> wrote:
> >> Hello,
> >> I have a model with over 1000 records and I want to select the top N
> >> records on field A that satisfy conditions on field B. (For example
> >> the youngest N records with a certain name.)
> >> My concern is if I only filter on field B and order in code
> >> afterwards, then I will miss some records not in the top 1000.
> >> I was hoping to create an index so that the results are always ordered
> >> by field A, but that doesn't seem to be possible.
> >> Ideas?
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