We have some performace issues when scaling with mysql clients. Standard solution is to scale oput with mysqld's instead. This solution is not accepted by all customers. Hence this feature. So we allow a mysqld to use several connections to the cluster effectively mimiking beind several mysqld's.
Minor task; no HLS needed. See LLD for details.
- add switch --ndb-cluster-connection-pool to set how many connections should be used - setup all connections at connect, store in array - allocate connections to thd's in a round robin fashion