If you move from 7.X to 0.8X or 1.0X you have to rebuild sstables as soon as possible. If you have large bloomfilters you can hit a bug where the bloom filters will not work properly.
On Thu, Aug 30, 2012 at 9:44 AM, Илья Шипицин <chipits...@gmail.com> wrote: > we are running somewhat queue-like with aggressive write-read patterns. > I was looking for scripting queries from live Cassandra installation, but I > didn't find any. > > is there something like thrift-proxy or other query logging/scripting engine > ? > > 2012/8/30 aaron morton <aa...@thelastpickle.com> >> >> in terms of our high-rate write load cassandra1.0.11 is about 3 (three!!) >> times slower than cassandra-0.7.8 >> >> We've not had any reports of a performance drop off. All tests so far have >> show improvements in both read and write performance. >> >> I agree, such digests save some network IO, but they seem to be very bad >> in terms of CPU and disk IO. >> >> The sha1 is created so we can diagnose corruptions in the -Data component >> of the SSTables. They are not used to save network IO. >> It is calculated while streaming the Memtable to disk so has no impact on >> disk IO. While not the fasted algorithm I would assume it's CPU overhead in >> this case is minimal. >> >> there's already relatively small Bloom filter file, which can be used for >> saving network traffic instead of sha1 digest. >> >> Bloom filters are used to test if a row key may exist in an SSTable. >> >> any explanation ? >> >> If you can provide some more information on your use case we may be able >> to help. >> >> Cheers >> >> >> ----------------- >> Aaron Morton >> Freelance Developer >> @aaronmorton >> http://www.thelastpickle.com >> >> On 30/08/2012, at 5:18 AM, Илья Шипицин <chipits...@gmail.com> wrote: >> >> in terms of our high-rate write load cassandra1.0.11 is about 3 (three!!) >> times slower than cassandra-0.7.8 >> after some investigation carried out I noticed files with "sha1" extension >> (which are missing for Cassandra-0.7.8) >> >> in maybeWriteDigest() function I see no option fot switching sha1 digests >> off. >> >> I agree, such digests save some network IO, but they seem to be very bad >> in terms of CPU and disk IO. >> why to use one more digest (which have to be calculated), there's already >> relatively small Bloom filter file, which can be used for saving network >> traffic instead of sha1 digest. >> >> any explanation ? >> >> Ilya Shipitsin >> >> >
