mongo geo index internal query

[Raxit Sheth]

Hi

When we use 2d/geo index, mongodb internally storing like this
(long,lat)/(x,y)-->geo-hash--->store geohash


When we retrive ($near query) :
convert given (long,lat),(x,y)
geohash
find distance accuracy required and strip remaining char from right
hand side of geo-hash
find 8 bounding box
Use 2d index on geohash (which is same as regular index, but geohash???)

Query :
index on geohash vs index on regular string has any difference in mongodb?


Purpose of query :
we want to put our on geo-retrival based on regular index by storing
geohash (simulating mongodb geo-index) as we need 2d index on more
than 2 field + $elemMatch with $near , both of which is currently not
possible.



Thanks
Raxit Sheth

[Raxit Sheth <Mobile 4 Mumbai>]

[Max Schireson]

I'm not 100% sure I understand the question.

I think you are asking about using indexes on strings where the content of the string is itself a geohash. It appears that you'd like to do a $ near query on the strings combined with some other queries.

I think what you are trying to do is not supported in mongodb.

Let me know if I misunderstood what you're asking.

-- Max

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[Raxit Sheth <Mobile 4 Mumbai>]

Max

what we want to do is, instead of using $near of mongo, want to
write our own $near
Instead of using "2d" index which is essentially B-Tree index on
geohash, want to write our own implementation @ App level


Raxit

On Nov 20, 1:53 pm, Max Schireson <mschire...@gmail.com> wrote:
> I'm not 100% sure I understand the question.
>
> I think you are asking about using indexes on strings where the content of
> the string is itself a geohash. It appears that you'd like to do a $ near
> query on the strings combined with some other queries.
>
> I think what you are trying to do is not supported in mongodb.
>
> Let me know if I misunderstood what you're asking.
>
> -- Max

[Max Schireson]

I've seen app level geo indexing built on top of non-geo indexes before with other technologies. No reason off the top of my head it won't work if done properly but it will be a lot of work...

-- Max

[Raxit Sheth <Mobile 4 Mumbai>]

Thanks!

Just finished implementing small hack for our app with Python.
Hope to see more advanced geo 2d&haystack in new version of mongo,
soon!

Raxit

[Max Schireson]

Working on more geo, stay tuned!