Re: unexpected result from to_tsvector

=# select ts_debug('simple', 'aaa@123-yyy.zzz');

                                 ts_debug                                  

---------------------------------------------------------------------------

 (email,"Email address",aaa@123-yyy.zzz,{simple},simple,{aaa@123-yyy.zzz})

(1 row)

But:

=# select ts_debug('simple', 'aaa@123_yyy.zzz');

                        ts_debug                         

---------------------------------------------------------

 (asciiword,"Word, all ASCII",aaa,{simple},simple,{aaa})

 (blank,"Space symbols",@,{},,)

 (uint,"Unsigned integer",123,{simple},simple,{123})

 (blank,"Space symbols",_,{},,)

 (host,Host,yyy.zzz,{simple},simple,{yyy.zzz})

(5 rows)

=# select ts_debug('simple', '123-yyy.zzz');

                       ts_debug                        

-------------------------------------------------------

 (host,Host,123-yyy.zzz,{simple},simple,{123-yyy.zzz})

(1 row)

=# select ts_debug('simple', '123_yyy.zzz');

                      ts_debug                       

-----------------------------------------------------

 (uint,"Unsigned integer",123,{simple},simple,{123})

 (blank,"Space symbols",_,{},,)

 (host,Host,yyy.zzz,{simple},simple,{yyy.zzz})

(3 rows)

But, this only has to do with 123 being recognized as a number, not with the underscore:

=# select ts_debug('simple', 'abc_yyy.zzz');

                       ts_debug                        

-------------------------------------------------------

 (host,Host,abc_yyy.zzz,{simple},simple,{abc_yyy.zzz})

(1 row)

In fact, the 123-yyy.zzz domain is not valid either according to the RFC (subdomain can't start with a digit), but since we already allow it, should we not allow 123_yyy.zzz to be recognized as a Host?  Then why not recognize aaa@123_yyy.zzz as an email address?