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From aaron morton <aa...@thelastpickle.com>
Subject Re: primary keys query
Date Mon, 14 May 2012 20:04:40 GMT
> 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 <dbrosius@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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