Re: SQL compatibility reminder: MySQL vs PostgreSQL

David Christensen <david(at)endpoint(dot)com> writes:
> On Mar 8, 2010, at 9:16 AM, Kevin Grittner wrote:
> Wolfgang Wilhelm <wolfgang20121964(at)yahoo(dot)de> wrote:
>>> Isn*t that a good time to think to put that question into the
>>> list of things PostgreSQL doesn*t want to do?
>>
>> Done.
>>
>> http://wiki.postgresql.org/wiki/Todo#Features_We_Do_Not_Want

> Does this conflict conceptually with the item from "Exotic Features"
> on the same page?:
> * Add pre-parsing phase that converts non-ISO syntax to supported syntax
> This could allow SQL written for other databases to run without
> modification.

I think the new item might be phrased a little too broadly. The problem
with mysql's GROUP BY behavior is not the syntax but the nonstandard
semantics, ie, that it will pick a random result row when the query is
underspecified. That means you can't just do a syntax translation,
which is what the "exotic" wishlist item seems to be envisioning.
I believe what that's actually about is the idea of converting things
like Oracle's CONNECT BY into SQL-spec constructs. Doing so wouldn't
break any existing PG-compatible applications, whereas messing with the
semantics of GROUP BY probably would.

regards, tom lane