> When one partition's data is extreme large, the write/read will slow? This is actually a good question, If a partition has near 2 billion rows, will writes or reads get too slow? My understanding is it shouldn't, as data is indexed inside a partition and when you read or write you are doing a binary search, so it should take log (n) time for the operation.
However, my practical experience tells me it can be a problem depending on the number of reads you do and how you do them. It your binary search takes 2 more steps, but for 1 billion reads, it could be considerably slow. Also, this search could be done on disk, as it depends a lot on how your cache is configured. Having a small amount per partition could be a Cassandra anti-pattern though, mainly if your reads can go across many partitions. I think there is no correct answer here, it depends on your data and on your application, IMHO. -Marcelo From: user@cassandra.apache.org Subject: Re: how many rows can one partion key hold? you might want to read here http://wiki.apache.org/cassandra/CassandraLimitations jason On Fri, Feb 27, 2015 at 2:44 PM, wateray <wate...@163.com> wrote: Hi all, My team is using Cassandra as our database. We have one question as below. As we know, the row with the some partition key will be stored in the some node. But how many rows can one partition key hold? What is it depend on? The node's volume or partition data size or partition rows size(the number of rows)? When one partition's data is extreme large, the write/read will slow? Can anyone show me some exist usecases. thanks!
