I wrote: > Perhaps this should be documented more clearly, but it's not obviously > wrong. If the domain declaration doesn't include an explicit COLLATE > then casting to the domain doesn't create an explicit collation > requirement. (That is, the domain *doesn't* have a specific > collation attached to it, any more than type text does.)
Perhaps we could improve matters like this?
diff --git a/doc/src/sgml/ref/create_domain.sgml b/doc/src/sgml/ref/create_domain.sgml index 81a8924926..e4b856d630 100644 --- a/doc/src/sgml/ref/create_domain.sgml +++ b/doc/src/sgml/ref/create_domain.sgml @@ -94,7 +94,8 @@ CREATE DOMAIN <replaceable class="parameter">name</replaceable> [ AS ] <replacea <listitem> <para> An optional collation for the domain. If no collation is - specified, the underlying data type's default collation is used. + specified, the domain has the same collation behavior as its + underlying data type. The underlying type must be collatable if <literal>COLLATE</literal> is specified. </para>
+1
The lack of any explicitness pushes evaluation down to the base type - which is a behavioral thing as opposed to some kind of attribute it possesses.
