Re: MySQL search query is not executing in Postgres DB

On Wed, Aug 29, 2012 at 06:39:37PM -0400, Tom Lane wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > On the more general issue, I continue to see minimal risk of harm
> > in allowing things like LPAD() to implicitly cast the first
> > argument to text.
> 
> Well, I see your point about LPAD(), but the problem is how to tell
> the difference between a harmless cast omission and an actual
> mistake that the user will be very grateful if we point out.  If we
> allow implicit casts to text in the general case in
> function/operator calls, we are definitely going to re-introduce a
> lot of room for mistakes.
> 
> Upthread you were complaining about how we'd reject calls even when
> there was only one possible interpretation.  I wonder whether
> there'd be any value in taking that literally: that is, allow use of
> assignment rules when there is, in fact, exactly one function with
> the right number of parameters visible in the search path.

+1 for this.

> The main downside I can see is that code that used to work is likely
> to stop working as soon as someone creates a potential overloading
> situation.  Worse, the error message could be pretty confusing,
> since if you had been successfully calling f(smallint) with f(42),
> you'd get "f(integer) does not exist", not something like "f() is
> ambiguous", after adding f(float8) to the mix.  This seems related
> to the confusing changes in regression test cases that I got in my
> experiments yesterday.  This may be sufficient reason to reject the
> idea, since the very last thing we need in this area is any
> degradation in the relevance of the error messages.

With the ANY* parameters introduced in the past few versions, there's
a lot less incentive to create this problem.  The trick here is
documenting the ANY* parameters in enough places to make sure that
incentive is reduced.

Cheers,
David.
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