[GENERAL] DOMAIN usability

[Rajesh Kumar Mallah]

Hi  , I think one of the usage patterns of  DOMAINS is to have size specifications and validity constraints at one place for easy administration of Database. Eg, instead of declaring email to be varchar(30) in 10s of tables  and putting a CHECK constraint for presence of  '@'  we could declare CREATE DOMAIN email_type varchar (30) CHECK ( value ~* '@') ; And users could use "email_type" in our CREATE TABLEs . There are two main issues (problems) 1. Suppose varchar(30) turns out to be too small oneday     and we want to increase it to varchar(100)  , what do i do ?     a)   Create a new domain ,     b)  Apply all  the constraints  on new domain     c)  Create new column in each of the tables and copy the old column     d)  drop the old domain cascaded.     any other more elegent method ? 2. Its difficult to see all the constraint defs on a domain .     information_schema.domain_constriants does not have the    definations just the names are present. Regards Mallah.