Re: SQL compatibility reminder: MySQL vs PostgreSQL

On Mon, Mar 8, 2010 at 12:43 PM, David Fetter <david(at)fetter(dot)org> wrote:
> On Mon, Mar 08, 2010 at 12:18:31PM -0500, Robert Haas wrote:
>> On Mon, Mar 8, 2010 at 12:10 PM, David Fetter <david(at)fetter(dot)org> wrote:
>> > On Mon, Mar 08, 2010 at 11:58:20AM -0500, Jaime Casanova wrote:
>> >> On Mon, Mar 8, 2010 at 4:17 AM, Pierre C <lists(at)peufeu(dot)com> wrote:
>> >> >
>> >> >> My opinion is that PostgreSQL should accept any MySQL syntax
>> >> >> and return warnings. I believe that we should access even
>> >> >> innodb syntax and turn it immediately into PostgreSQL tables.
>> >> >> This would allow people with no interest in SQL to migrate
>> >> >> from MySQL to PostgreSQL without any harm.
>> >> >
>> >> > A solution would be a SQL proxy (a la pgpool) with query
>> >> > rewriting.
>> >>
>> >> This sounds like a better idea...
>> >
>> > Aside from that little "halting problem" issue, it sounds
>> > wonderful.  You do know that SQL is Turing-complete, right?
>>
>> That seems largely irrelevant to the problem at hand.  It's not
>> impossible to do syntactic transformations from one Turing-complete
>> langauge to another; if it were, there could be no such thing as a
>> compiler.
>
> MySQL's SQL isn't Turing complete.

It still doesn't matter. Turing-completeness does not preclude syntax
transformation. Non-Turing completeness, even less so.

...Robert