On Jun 5, 2008, at 11:28, Martijn van Oosterhout wrote:
On Thu, Jun 05, 2008 at 11:18:26AM -0700, David E. Wheeler wrote:
I'm working on a custom data type based on TEXT that does case-
insensitive, locale-aware comparisons, essentially by calling LOWER()
to compare values.
What makes this different from the citext project?
citext is not locale-aware; please Tom's comments in the "Case-
Insensitve Text Comparison" thread.
However, thanks to the implicit cast PostgreSQL finds more than one
candidate operator when I compare properly casted values:
try=# select 'a'::lctext = 'a'::text;
ERROR: operator is not unique: lctext = text
LINE 1: select 'a'::lctext = 'a'::text;
^
What would you want postgresql to choose in this case.
I was thinking that the ::text should be cast to ::lctext, as that's
how `'a'::lctext = 'a'` works, but I keep going back and forth in my
mind. Maybe 'a'::lctext should not equal 'A'::text.
Whichever way
you want it, make that direction implicit and the other direction
assignment.
I'm sure I'm missing something simple here. How do I make it assignment?
Having A->B and B->A both as implicit just leads to
ambiguity.
Huh. That's what citext has, too:
CREATE CAST (citext AS text) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (text AS citext) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (citext AS varchar) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (varchar AS citext) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (citext AS bpchar) WITHOUT FUNCTION AS IMPLICIT;
CREATE CAST (bpchar AS citext) WITHOUT FUNCTION AS IMPLICIT;
But I agree that there is confusion for PostgreSQL here.
Thanks,
David
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