Hi there,
I noticed that check constraint definitions are sometimes
rewritten/normalized on input, and I was hoping to understand that a little
better.
For instance, if I create this table with a check constraint:
create table foo (
val varchar,
constraint val_valid check (val in ('a','b','c'))
);
and then dump the schema with pg_dump, it looks more like this:
CREATE TABLE public.foo (
val character varying,
CONSTRAINT val_valid CHECK (((val)::text = ANY ((ARRAY['a'::character
varying, 'b'::character varying, 'c'::character varying])::text[])))
);
However, if I then recreate the schema from that dump, and then dump with
pg_dump a second time, it ends up different again:
CREATE TABLE public.foo (
val character varying,
CONSTRAINT val_valid CHECK (((val)::text = ANY (ARRAY[('a'::character
varying)::text, ('b'::character varying)::text, ('c'::character
varying)::text])))
);
I'm working in a Ruby on Rails application where the schema is periodically
dumped to a structure.sql file on disk. So, it would be convenient if the
constraint definition was "stable" (otherwise, there's unnecessary noise in
our version control history)
Is it expected that the second form is rewritten into the third form? It
seems a bit odd to see all the type casting going on, but maybe there is a
good reason for that. (Maybe this is an issue with using varchar instead of
text?)
Regards,
Stuart
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