question about bulk loading

[scwf]

Hi all,
  i have a question about phoenix bulk loading:

  hbase-cluster: 4 nodes, 1 HMaster 4 Regionser

  Create a table using phoenix, the empty table in hbase's regions num is 0

  After bulkloading dataset,
        Size      :  586M
        Rows     :  1,000,000
        Columns  :   134

  its regions num change to 3

  how phoenix control the regions num of the table after bulk loading and can i 
config this?

  thanks.