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From Nick Dimiduk <ndimi...@gmail.com>
Subject Re: Spatial data posting in HBase
Date Sat, 12 Oct 2013 23:16:02 GMT
You can treat a geohash of a fixed precision as a tile and calculate the
neighbors of that tile. This is precisely what I did in the chapter in
HBaseIA. In that way, it's no different than a tile system.


On Sat, Oct 12, 2013 at 11:33 AM, Michael Segel
<michael_segel@hotmail.com>wrote:

> Adrien,
>
> In terms of efficiency...
>
> A general solution that can be applied to all problems in all areas is
> going to be best.
> Geohash gets ugly when you're around the equator.  You can have two points
> literally a couple of km away that would have two very different geo hashes.
>
> So if you tile the globe, depending on the size of the tile, you calculate
> the tile, its surrounding tiles (if necessary) and then sweep through the
> data to find your object.
>
> I'm not suggesting you not to use geohash, just that its not going to be
> the most efficient.
>
> Note that the the downside to tiling is that if you're doing a geospatial
> index... your data volume explodes because you are storing references to
> the data at different tile levels.
>
> Its a trade off.
>
>
>
> On Oct 12, 2013, at 2:34 AM, Adrien Mogenet <adrien.mogenet@gmail.com>
> wrote:
>
> > Michael, don't you think Geohashes can be satisfying and well-suited for
> > many cases anyway? Searching in a bounding box or arbitrary polygon is
> not
> > that heavy with Geohash, even on edge conditions. The biggest risk IMHO
> is
> > to have to deal with tons of invalid extra points if the geohash query is
> > not accurate enough and your points distribution is very sparse so that
> > many points will be found in a geohash despite they don't respond to your
> > query criteria.
> >
> > However, if your query embeds enough bits of precision, Geohashes offer
> > some nice guarantees for distributed databases and your queries should
> > remain efficient enough.
> >
> > Another worst case of course is to look for K-NN since Geohash is not a
> > real longest-common-prefix algorithm but once again, if your points
> > distribution is approximately well balanced, this works not that bad
> > without doing lots of recursive queries or fetching tons of useless data
> > (but I do agree looking into your tiles would probably be more
> appropriate
> > in that case).
> >
> > I'm planning to write an article on that points, so further technical
> > arguments are welcome :-}
> >
> > On Thu, Oct 10, 2013 at 7:51 PM, Michael Segel <
> msegel_hadoop@hotmail.com>wrote:
> >
> >> HBase in Action goes through great depth of showing you how you could
> >> implement GIS information in HBase.
> >>
> >> Unfortunately there are issues with Geohash and edge conditions which
> make
> >> it difficult to use when you're dealing with data on an edge of a
> quadrant.
> >>
> >> A better way would be to create a point (geospatial point object) and
> >> store it in a single column.
> >> (This goes beyond the example of what's in the book. ) And then index
> the
> >> data by tiles.
> >>
> >>
> >> The downside is that you end up creating a lot more data…
> >>
> >> Take a look at some of the stuff Boris Lublinsky published on InfoQ.
> There
> >> are also other articles on the net….
> >>
> >> On Oct 9, 2013, at 1:35 PM, Otis Gospodnetic <
> otis.gospodnetic@gmail.com>
> >> wrote:
> >>
> >>> The point is that there are options (multiple different hammers) if
> >>> HBase support for geospatial is not there or doesn't meet OP's needs.
> >>>
> >>> Otis
> >>> --
> >>> Solr & ElasticSearch Support -- http://sematext.com/
> >>> Performance Monitoring -- http://sematext.com/spm
> >>>
> >>>
> >>>
> >>> On Wed, Oct 9, 2013 at 11:14 AM, Michael Segel
> >>> <msegel_hadoop@hotmail.com> wrote:
> >>>> And Solr has what to do with storing data in HBase?
> >>>>
> >>>> I guess its true… if all you have is a hammer…
> >>>>
> >>>> The point I was raising was that geohash isn't the most efficient way
> >> to go when you look at the problem at a global level…
> >>>>
> >>>> On Oct 9, 2013, at 9:34 AM, Otis Gospodnetic <
> >> otis.gospodnetic@gmail.com> wrote:
> >>>>
> >>>>> Consider using Solr, which provides a lot of geospatial search
> support.
> >>>>>
> >>>>> Otis
> >>>>> Solr & ElasticSearch Support
> >>>>> http://sematext.com/
> >>>>> On Sep 24, 2013 8:29 AM, "cto" <ankur5.c@tcs.com> wrote:
> >>>>>
> >>>>>> Hi ,
> >>>>>>
> >>>>>> I am very new in HBase. Could you please let me know , how to
insert
> >>>>>> spatial
> >>>>>> data (Latitude / Longitude) in HBase using Java .
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>> --
> >>>>>> View this message in context:
> >>>>>>
> >>
> http://apache-hbase.679495.n3.nabble.com/Spatial-data-posting-in-HBase-tp4051123.html
> >>>>>> Sent from the HBase User mailing list archive at Nabble.com.
> >>>>>>
> >>>>
> >>>
> >>
> >>
> >
> >
> > --
> > Adrien Mogenet
> > http://www.borntosegfault.com
>
> The opinions expressed here are mine, while they may reflect a cognitive
> thought, that is purely accidental.
> Use at your own risk.
> Michael Segel
> michael_segel (AT) hotmail.com
>
>
>
>
>
>

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