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From Sylvain Lebresne <sylv...@yakaz.com>
Subject Re: Just starting to play with Cassandra: (Surely) Dumb Question
Date Sat, 17 Apr 2010 15:46:09 GMT
On Sat, Apr 17, 2010 at 5:38 PM, Lucas Di Pentima
<lucas@di-pentima.com.ar> wrote:
> 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?

Yes

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

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