incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Dave Brosius <dbros...@baybroadband.net>
Subject Re: SSTable format
Date Sat, 14 Jul 2012 02:18:42 GMT
While in memory cassandra calls it a MemTable, but yes sstables are 
write-once, and later combined with others into new ones thru compaction.



On 07/13/2012 09:54 PM, Michael Theroux wrote:
> Thanks for the information,
>
> So is the SStable essentially kept in memory, then sorted and written to disk on flush?
 After that point, an SStable is not modified, but can be written to another SStable through
compaction?
>
> -Mike
>
> On Jul 13, 2012, at 8:22 PM, Rob Coli wrote:
>
>> On Fri, Jul 13, 2012 at 5:18 PM, Dave Brosius<dbrosius@baybroadband.net>  wrote:
>>> It depends on what partitioner you use. You should be using the
>>> RandomPartitioner, and if so, the rows are sorted by the hash of the row
>>> key. there are partitioners that sort based on the raw key value but these
>>> partitioners shouldn't be used as they have problems due to uneven
>>> partitioning of data.
>> The formal way this works in the code is that SSTables are ordered by
>> "decorated" row key, where "decoration" is only a transformation when
>> you are not using OrderedPartitioner. FWIW, in case you see that
>> "DecoratedKey" syntax while reading code..
>>
>> =Rob
>>
>> -- 
>> =Robert Coli
>> AIM&GTALK - rcoli@palominodb.com
>> YAHOO - rcoli.palominob
>> SKYPE - rcoli_palominodb
>


Mime
View raw message