On Wed, Dec 24, 2008 at 6:41 PM, Erik Jones <ejones@xxxxxxxxxxxxxx> wrote:>> On Dec 24, 2008, at 12:04 PM, Grzegorz Jaśkiewicz wrote:>>> On Wed, Dec 24, 2008 at 6:12 PM, Erik Jones <ejones@xxxxxxxxxxxxxx> wrote:>>>>>> Yes, and columns have default values, too, which are not tied to their>>> datatype's default value (if it even has one). ALTER TABLE initializes>>> rows>>> to have the new *column's* default. A column of some domain type could>>> easily have some default other than the domain's default and, in fact, if>>> you don't specify a default for the column then it's default is NULL.>>>> the whole thing about domains, is that you specify type and default,>> and even check constraint. And I did specify default - hence I would>> expect it to be set to that value!!>> You really need to understand the difference between a domain's default and> a column's default. The ALTER TABLE docs specifically say that if you don't> specify a default for the new *column* then that column is set to NULL for> all rows. That is not the same as not providing a value for a column of> some domain type with a default in an INSERT statement. A domain with a> default does not specify that it can not be set to null: I disagree. It's quite natural and reasonable to have defaults passedthrough the composite type as the OP expects. This is a possibleimprovement (TODO?) in the way composite types are handled. There area couple of other loopholes in domans/composite types: * domains can't be stacked in an array (but you can if they arewrapped in a composite type)* check constraints not enforced for composite type on cast (but arefor domains)* alter type should be expanded to allow things that are currentlypossible via alter table (currently a TODO, IIRC), or createtable/alter table should be adjusted for better handling of types, and'create type as' should be deprecated. The latter is what I thinkshould happen, but it's controversial :-). In the meantime the OP has to decide what he wants to use more,composite types or default values on domains. merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx)To make changes to your subscription:http://www.postgresql.org/mailpref/pgsql-general
