[轉]database.yml &, <<, *

http://stackoverflow.com/questions/6651275/what-do-the-mean-in-this-database-yml-file

The & marks an alias for the node (in your example &defaultaliases the development node as "default")

* references the aliased node with the name "default".

<<: inserts the content of that node.

test: &test <<: *default


default_env:
  <<: *production