Re: MySQL search query is not executing in Postgres DB

Jeff Davis <pgsql@j-davis.com>

From: Jeff Davis <pgsql@j-davis.com>
To: Simon Riggs <simon@2ndQuadrant.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Robert Haas <robertmhaas@gmail.com>, Peter Eisentraut <peter_e@gmx.net>, Greg Stark <stark@mit.edu>, Bruce Momjian <bruce@momjian.us>, Andrew Dunstan <andrew@dunslane.net>, Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>, premanand <kottiprem@gmail.com>, pgsql-hackers@postgresql.org
Date: 2012-11-27T09:59:04Z
Lists: pgsql-hackers
On Wed, 2012-11-21 at 15:27 +0000, Simon Riggs wrote:
> It would be useful if we issued a NOTICE when an ambiguity is
> introduced, rather than when using it.
> 
> Like Bison's reporting of reduce conflicts.

This brings up a very important point, which is that a lot of the code
is frozen in applications yet invisible at DDL time. So we have to be
careful that DDL changes have a reasonable impact on the ability to
continue to compile and execute the previously-working SQL received from
the applications.

In other words, as I said in another reply, we want to avoid cases where
something seemingly innocuous (like creating a function) causes
previously-working SQL to fail due to ambiguity.

As Tom said, detecting the ambiguity at DDL time is not easy, so I'm not
suggesting that. And I know that creating a function can already cause
previously-working SQL to fail. I'm just saying we should be careful of
these situations and not make them more likely than necessary.

Regards,
	Jeff Davis