On Thu, May 29, 2014 at 1:08 PM, DuyHai Doan <doanduy...@gmail.com> wrote:
> Hello Robert > > There are some maths involved when considering the performance of > secondary index in C* > Yes, these are the maths which are behind my FIXMEs in the original post. I merely have not had time to explicitly describe them in the context of that draft post. Thank you for doing so! When I reference them in my eventual post, I will be sure to credit you. > Because of its distributed nature, finding a *good* use-case for 2nd > index is quite tricky, partly because it depends on the query pattern but > also on the cluster size and data distribution. > Yep, and if you're doing this tricky thing, you probably want less opacity and more explicit understanding of what is happening under the hood and you want to be sure you won't run into a bug in the implementation, hence manual "secondary index" CFs. > Apart from the performance aspect, secondary index column families use > SizeTiered compaction so for an use case with a lot of update you'll have > plenty of tombstones... I'm not sure how end user can switch to Leveled > Compaction for 2nd index... > Per Aleksey, secondary index column families actually use the compaction strategy of the column family they index. I agree that this seems weird, and is likely just another implementation detail you relinquish control of for the convenience of 2i. =Rob
