Re: SQL-spec incompatibilities in similar_escape() and related stuff

On Mon, May 13, 2019 at 2:39 PM Andrew Gierth
<andrew(at)tao11(dot)riddles(dot)org(dot)uk> wrote:
> Or we could kill off postfix operators...

/me helps Andrew hijack the thread.

We wouldn't even have to go that far. We could just restrict it to a
specific list of operators that are hard-coded into the lexer and
parser, like say only '!'.

Even if we killed postfix operators completely, the number of users
who would be affected would probably be minimal, because the only
postfix operator we ship is for factorial, and realistically, that's
not exactly a critical thing for most users, especially considering
that our implementation is pretty slow. But the number of people
using out-of-core postfix operators has got to be really tiny --
unless, maybe, there's some really popular extension like PostGIS that
uses them.

I think it's pretty clear that the theoretical beauty of being able to
handle postfix operators is not worth the tangible cost they impose on
our parser. We're losing more users as a result of SQL that other
systems can accept and we cannot than we are gaining by being able to
support user-defined postfix operators. The latter is not exactly a
mainstream need.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company