> So it seems it's not a good idea, to use Cassandra like that?
Right. It's basically a table scan. 

Here is some background on the approach simple geo took to using Cassandra...
http://www.readwriteweb.com/cloud/2011/02/video-simplegeo-cassandra.php

Also PostGis for Postgress seems popular http://postgis.refractions.net/

Hope that helps. 


-----------------
Aaron Morton
Freelance Developer
@aaronmorton
http://www.thelastpickle.com

On 12/05/2012, at 4:23 AM, cyril auburtin wrote:

> I was thinking of a CF with many many rows with id, type, latitude and 
> longitude (indexed), and do geolocation queries: type=all and lat < 43 and 
> lat >42.9 and lon < 7.3 and lon > 7.2
> 
> where all rows have type=all
> (at least try how Cassandra deals with that)
> So it seems it's not a good idea, to use Cassandra like that?
> 
> There's also the possibly to do in parallel, other CF, with latitude in rows, 
> that will be sorted, so an indexed query can give us the right latidue range, 
> and then just query with logitude < and >
> 
> What do you think of that
> 
> thanks
> 
> 2012/5/11 Dave Brosius <dbros...@mebigfatguy.com>
> Inequalities on secondary indices are always done in memory, so without at 
> least one EQ on another secondary index you will be loading every row in the 
> database, which with a massive database isn't a good idea. So by requiring at 
> least one EQ on an index, you hopefully limit the set of rows that need to be 
> read into memory to a manageable size. Although obviously you can still get 
> into trouble with that as well.
> 
> 
> 
> 
> On 05/11/2012 09:39 AM, cyril auburtin wrote:
> Sorry for askign that
> but Why is it necessary to always have at least one EQ comparison
> 
> [default@Keyspace1] get test where birth_year>1985;
>    No indexed columns present in index clause with operator EQ
> 
> It oblige to have one dummy indexed column, to do this query
> 
> [default@Keyspace1] get test where tag=sea and birth_year>1985;
> -------------------
> RowKey: sam
> => (column=birth_year, value=1988, timestamp=1336742346059000)
> 
> 
> 
> 

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