| From: | Merlin Moncure <mmoncure(at)gmail(dot)com> |
|---|---|
| To: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
| Cc: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, Bruce Momjian <bruce(at)momjian(dot)us>, Jeff Davis <pgsql(at)j-davis(dot)com>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Robert Haas <robertmhaas(at)gmail(dot)com>, Greg Stark <stark(at)mit(dot)edu>, Andrew Dunstan <andrew(at)dunslane(dot)net>, Heikki Linnakangas <heikki(dot)linnakangas(at)enterprisedb(dot)com>, premanand <kottiprem(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: MySQL search query is not executing in Postgres DB |
| Date: | 2012-11-27 22:24:05 |
| Message-ID: | CAHyXU0wgvJ0ziHwRer2cb4DR1-Ha_TErFm0EgGpy_tCXAidwBw@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Nov 27, 2012 at 4:09 PM, Peter Eisentraut <peter_e(at)gmx(dot)net> wrote:
> On 11/27/12 12:07 PM, Merlin Moncure wrote:
>> Speaking of polymorphism, why not just implement lpad()'s first
>> argument as 'anyelement'?
>
> One of the arguments made here was that lpad(not-text) *should* fail.
Well, sure. My point is: why do we need to break the casting
machinery when we can simply tweak a few of the standard functions on
portability grounds?
Robert's case on lpad() has merit in the sense it has unambiguous
meaning regardless of input type; polymorphic input types were
designed to solve *exactly* that problem. SQL portability is a
secondary but also important argument.
That said, md5() surely needs some type of cast or interpretation of
non-text types. ditto to_timestamp(), etc. So messing around with
the casting rules is surely the wrong answer. I think if you relaxed
the function sigs of a few functions on this page
(http://www.postgresql.org/docs/9.2/interactive/functions-string.html),
most reported problems would go away.
One thing that worries me is introducing ambiguous cases where
previously there weren't any though.
merlin
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