limit in sub query turn out to be not supported

git-svn-id: http://hustoj.googlecode.com/svn/trunk@2202 19ab8b60-bd6c-11dd-baed-41e496641fac
add flex

git-svn-id: http://hustoj.googlecode.com/svn/trunk@2203 19ab8b60-bd6c-11dd-baed-41e496641fac
flex

git-svn-id: http://hustoj.googlecode.com/svn/trunk@2204 19ab8b60-bd6c-11dd-baed-41e496641fac
default sleep_time=1

git-svn-id: http://hustoj.googlecode.com/svn/trunk@2205 19ab8b60-bd6c-11dd-baed-41e496641fac
faster

git-svn-id: http://hustoj.googlecode.com/svn/trunk@2206 19ab8b60-bd6c-11dd-baed-41e496641fac