Cassandra does not provide access to multiple versions of the same column. It is essentially implementation detail.
All mutations are written to the commit log in a binary format, see the o.a.c.db.RowMutation.getSerializedBuffer() (If you want to tail it for analysis you may want to change commitlog_sync in cassandra.yaml) Here is post about looking at multiple versions columns in an sstable http://thelastpickle.com/2011/05/15/Deletes-and-Tombstones/ Remember that not all "versions" of a column are written to disk (see http://thelastpickle.com/2011/04/28/Forces-of-Write-and-Read/). Also compaction will compress multiple versions of the same column from multiple files into a single version in a single file . Hope that helps. ----------------- Aaron Morton Freelance Developer @aaronmorton http://www.thelastpickle.com On 14/05/2012, at 9:50 PM, Felipe Schmidt wrote: > Yes, I need this information just for academic purposes. > > So, to read old data values, I tried to open the Commitlog using tail > -f and also the log files viewer of Ubuntu, but I can not see many > informations inside of the log! > Is there any other way to open this log? I didn't find any Cassandra > API for this purpose. > > Thanks averybody in advance. > > Regards, > Felipe Mathias Schmidt > (Computer Science UFRGS, RS, Brazil) > > > > > 2012/5/14 zhangcheng2 <zhangche...@software.ict.ac.cn>: >> After compaciton, the old version data will gone! >> >> ________________________________ >> zhangcheng2 >> >> From: Felipe Schmidt >> Date: 2012-05-14 05:33 >> To: user >> Subject: Retrieving old data version for a given row >> I'm trying to retrieve old data version for some row but it seems not >> be possible. I'm a beginner with Cassandra and the unique aproach I >> know is looking to the SSTable in the storage folder, but if I insert >> some column and right after insert another value to the same row, >> after flushing, I only get the last value. >> Is there any way to get the old data version? Obviously, before compaction. >> >> Regards, >> Felipe Mathias Schmidt >> (Computer Science UFRGS, RS, Brazil) >>
