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From Lucas Di Pentima <lu...@di-pentima.com.ar>
Subject Re: Just starting to play with Cassandra: (Surely) Dumb Question
Date Sat, 17 Apr 2010 15:38:49 GMT
Hello Sylvain,

El 17/04/2010, a las 12:09, Sylvain Lebresne escribió:

> On Sat, Apr 17, 2010 at 4:52 PM, Lucas Di Pentima
> <lucas@di-pentima.com.ar> wrote:
>> Hello Jonathan,
>> 
>> I supposed the same, that's why I tried the count_columns() call, but when I try
it with some big SCF, I get the same error message:
>> 
>> Thrift::TransportException: Socket: Timed out reading 4096 bytes from 127.0.0.1:9160
>> 
>> Should I use count_columns() or is there any other way to know how much columns exists?
> 
> get_count() (that, even though I don't know the ruby gem, is most
> probably used by
> count_columns() under the hood) actually query the whole row and
> simply return the number
> of column founded. Hence the only thing you gain by counting columns
> instead of requesting
> them is that you don't have to pull all the columns over the network.
> Hence counting is (roughly) as costly as requesting the whole row and
> as such, it is no wonder
> it timeout in your case.
> 


Thanks for the explanation, so in the case I need to fetch all the columns on a big ColumnFamily,
I should request a few thousands at a time as Jonathan told me, using the start parameter,
until I get no more columns, am I right?


Best regards,
--
Lucas Di Pentima - Santa Fe, Argentina
Jabber: lucas@di-pentima.com.ar
MSN: ldipenti75@hotmail.com





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