hbase -regions assignment(in creating table)

as iwinit dug in source codes[1],the 'regions assigment' in hbase is complex and trickle.there are many of zk related events across master and rs,and huge of pre-post processes in it.

below is a abstract view i figured out:

 

 

 against zookeeper,u will find the many of interesting processing models like these:

a.A creates znodes in zk with raw state;

b.B does some processes that it should expect;then update the state ;

c.A receives that events,then finalize the znode and post-business

 

last,i wonder to declare that some important zk related events across this assignment:

 

 

 

 also,below is the zookeeper events trigger basics:

 that means there is a 3-d trigger model:

Enumeration of types of events that may occur on the ZooKeeper

EventType	tirgger creation point(register)	trigger event(operation)	usage
NodeCreated	exists	create a znode
NodeDeleted	exists,getData, getChildren(this is the case of deletion of parent znode)	delete a znode
NodeDataChanged	exists,getData	update/set a znode with new/old data
NodeChildrenChanged	getChildren	create/delete a child znode

 

in other words,by simplely,u can:

 

make a 'trigger operation' -> then through previously 'register' -> then get a appropriate callback 'EventType'

 

 

but one thing i have no idea is which register will be triggered first when updating a znode if i use both 'exists' and 'getData' register on the same znode?

i this there will be some rules to do this in zk.so i will check for the source also soon later ...TODO

 

 

ref:

[1] [HBase]Region assignment

hadoop-guide