3400+ Keyspaces

(4 posts) (3 voices)

• Started 10 months ago by nvt
• Latest reply from nvt
• This topic is not a support question

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1. 

   nvt
   Member

   Hello,

   I realize it is not a good idea to create more than one (or a few) keyspaces. But in our current design we are required to create 3400+ keyspaces, each with 12 column families (one of them is a super column). I have created one large cli file with statements to create the keyspaces, and the column families within the keyspaces, and am loading it using cassandra-cli. The rate of keyspaces creation is about 9 per minute when the loading first starts. After a few hours, the rate of keyspaces creation comes down to about 3 per minute. I have tried lowering the compaction throughput to 0, but the rate of keyspaces creation is still sluggish. What can I do to increase the rate of keyspaces creation?

   Thanks
   Naga Vijay

   Posted 10 months ago #
2. 

   xedin
   Member

   The bottleneck here is that data about schema migrations if flushed to disk every time when schema update is applied, if you are using Cassandra 1.1.x you can try to run keyspace creation using multitheaded . Be aware that if we are talking about Cassandra <= 1.0.x as migrations are distributed across all nodes of the cluster so some of the nodes could build up pretty big migration queues - as migrations should be applied in-order - depending on the network/node load which would lead to schema disagreements, although if your nodes are >= 1.1.x it shouldn't be a concern as migrations are send it form of row mutations which are must smaller and don't require in-order apply.

   Posted 10 months ago #
3. 

   thobbs
   Administrator

   Also, if you have 3400 * 12 = 40800 column families, you need a minimum of 40GB of heap space, which will not turn out well at all. I suggest using a different approach.

   Posted 10 months ago #
4. 

   nvt
   Member

   Agreed, after trying out everything possible (multiple KS, multiple CF), we are planning a different approach.

   Posted 10 months ago #

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