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From TuxRacer69 <tuxrace...@gmail.com>
Subject Re: newbie questions about Cassandra J. Ellis presentation
Date Fri, 13 Nov 2009 09:34:07 GMT
Thanks Edmond for your answer.
I added this to the FAQ http://wiki.apache.org/cassandra/FAQ
as even google does not seem to know anything about "Sorted Strings Table"
http://www.google.com/search?q=%22Sorted+Strings+Table%22 ;)

Alex

Edmond Lau wrote:
> On Fri, Nov 13, 2009 at 12:20 AM, TuxRacer69 <tuxracer69@gmail.com> wrote:
>   
>> Hello Cassandra Users!
>>
>> On the wiki page:
>> http://wiki.apache.org/cassandra/ArticlesAndPresentations
>> there is a link to J. Ellis pdf:
>> http://assets.en.oreilly.com/1/event/27/Cassandra_%20Open%20Source%20Bigtable%20+%20Dynamo%20Presentation.pdf
>>
>>
>> At page 41 we have: (Roadmap) Cassandra 0.5
>> Cassandra 0.5
>> Millions of columns per row
>> This will require another data format change
>>
>> Question 1:
>> -----------------
>> Is there any Jira logged for this change yet?
>> I'd like to understand
>> a) if a full data rebuild will be necessary for upgrading from 0.4.X to 0.5
>> b) what the limitations currently are in Cassandra.
>> - How many keys per column family
>> - How many columns per key in a standard column family
>> - How many columns per key in a super column family, and how many subcolumns
>> within a supercolumn key
>>
>> Page http://wiki.apache.org/cassandra/CassandraLimitations
>> says "The main limitation on column and supercolumn size is that all data
>> for a single key and column must fit (on disk) on a single machine in the
>> cluster." but that does not really answer the questions above (as know we
>> can have 1Tb disk cheaply)
>>
>> Question 2:
>> ----------------
>> Page 15 and 16: Architecture layer.
>> How could we defined Memtables and SStables? What the two 'S' stand for in
>> SSTable?
>>     
>
> A Memtable is Cassandra's in-memory representation of key/value pairs
> before the data gets flushed to disk as an SSTable.  An SSTable
> (terminology borrowed from Google) stands for Sorted Strings Table and
> is a file of key/value string pairs, sorted by keys.
>
> Edmond
>
>   
>> Thanks a lot
>> Alex
>>
>>
>>
>>     


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