[datatable-help] Secondary keys

[Frank Erickson]

I figure it means that -- if I set2key(DT,V1,V2) -- you store the integer
vectors order(V1), order(V1,V2) ...(are both needed?)...with the object and
somehow use that information to permit the use of the secondary key just
like (from the user's perspective) the primary key (joining on it with
appropriate syntax, automatically speeding up anything ending in by='V1,V2'
or by=V1 and whatever else).

Matt says in the FR: "add secondary order vectors as attribute to DT"


On Wed, Oct 9, 2013 at 12:04 AM, Chinmay Patil <chinmay.patil at gmail.com>wrote:

> I just used the terminology that was used in issue
> https://r-forge.r-project.org/tracker/index.php?func=detail&aid=1007&group_id=240&atid=978
> by Matt.
>
> Essentially, it would mean that whole table is also pre-sorted by some
> other column than it's primary key and that sort order is also saved.
> Perhaps, Matt would shed some light on it?
>
>
> On Wed, Oct 9, 2013 at 11:56 AM, Eduard Antonyan <
> eduard.antonyan at gmail.com> wrote:
>
>> I understand the problem you want solved (fast search by e.g. second key
>> element), but I don't understand what secondary keys would mean/be...?
>> On Oct 8, 2013 10:48 PM, "Chinmay Patil" <chinmay.patil at gmail.com> wrote:
>>
>>> Eduard,
>>>
>>> Details of the issue raised are in this question.
>>>
>>> http://stackoverflow.com/questions/15769837/
>>>
>>>
>>> On Tue, Oct 8, 2013 at 10:47 PM, Eduard Antonyan <
>>> eduard.antonyan at gmail.com> wrote:
>>>
>>>> I don't think I understand what secondary keys are (supposed to be),
>>>> can someone who knows please elaborate?
>>>>
>>>>
>>>> On Sun, Oct 6, 2013 at 12:17 AM, Chinmay Patil <chinmay.patil at gmail.com
>>>> > wrote:
>>>>
>>>>> Hi devs,
>>>>>
>>>>> I was wondering if there are any plans to implement this feature.
>>>>>
>>>>>
>>>>> https://r-forge.r-project.org/tracker/index.php?func=detail&aid=1007&group_id=240&atid=978
>>>>>
>>>>> Alternatively, is there a way to refer to key of the data.table object
>>>>> in "J" function used for subsetting?
>>>>>
>>>>> _______________________________________________
>>>>> datatable-help mailing list
>>>>> datatable-help at lists.r-forge.r-project.org
>>>>>
>>>>> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/datatable-help
>>>>>
>>>>
>>>>
>>>
>
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