Re: SV: Help with getting Key range with some column limitations

[Jone Lura]

 Thanks for you suggestions.

I tried to iterate them, however I could not get it to work (pretty sure 
its my code). Im still not to familiar with Cassandra, so could you 
provide a small example?

The key count could be up to atleast 20k and maybe more, and users 
should not wait for more than 10 seconds for their map, so I also want 
to investigate the plugin suggestion. Does the plugin exist? or do I 
have to develop it myself? Are there any documentation on plugin 
development for Cassandra?

Best regards

Jone


On 19/08/2010 08:42, Thorvaldsson Justus wrote:

You should iterate through them, get 200 then go get the next 200 and 
so on.

Also if checking a bounding box to another.. perhaps try sorting them 
so you could start looking at both ends, perhaps make the iteration 
smaller until match somehow?

Just my simple coins, also upgrading will probably be needed to 
iterate through RP because of bugs. But that should be simple enough 
to 6.4

/Justus

*Från:* Jone Lura [mailto:jone.l...@ecc.no]
*Skickat:* den 18 augusti 2010 20:32
*Till:* user@cassandra.apache.org
*Ämne:* Help with getting Key range with some column limitations

Hi,

We are trying to implement Cassandra to replace one of our biggest SQL 
tables, and so far we got it working.

However, for testing I'm using Cassandra 0.6.2, Java and Pelops. 
(Pelops not that important for my question) and need suggestions on 
how to solve a problem retrieving a key range based on the following.

<Keyspace Name="AIS">

<ColumnFamily Name="Location"

        ColumnType="Super"

        CompareWith="LongType"

        KeysCached="100%"

        CompareSubcolumnsWith="UTF8Type" />

     ...

</Keyspace>

The super column got columns for longitude and latitude.

 1. Need to get get max long number for key

 2. The key should also have supercolumns latitude and longitude 
column intersecting (inside) with a given boundingbox.

Currently I'm doing like this

        KeyRange keyRange = new KeyRange();

        keyRange.setStart_key("");

        keyRange.setEnd_key("");

        keyRange.setCount(700);

And checking every row in db if it match my bounding box.

But there are a lot more than 700 keys.. and if i set a higher count, 
the get_range_slice get a Timeout Exception.

Any ideas?

Best Regards

Jone