CHECK constraint (true) causes dumps with parse errors
Dear Gurus,
Version: 7.3.3, 7.4.8
I don't know for sure, but something like this happened when dumping our
server from 7.3 to 7.4. Actually, it seems to be a problem in 7.4 (maybe
also in 7.3, but unlikely -- see below, "our original way").
# create table foo (bar int, constraint foobar check (true or bar=1));
CREATE TABLE
# \d foo
Table "public.foo"
Column | Type | Modifiers
--------+---------+-----------
bar | integer |
Check constraints:
"foobar" CHECK (true OR bar = 1)
# drop table foo;
DROP TABLE
# create table foo (bar int, constraint foobar check (true));
CREATE TABLE
# \d foo
Table "public.foo"
Column | Type | Modifiers
--------+---------+-----------
bar | integer |
Check constraints:
"foobar" CHECK ()
Yours,
--
G.
---------------- our original way we found the problem:
-- original create command:
CREATE TABLE foo (
bar int,
CONSTRAINT foobar CHECK (true or bar=1)
);
-- 7.3 dump:
CREATE TABLE foo (
bar int,
CONSTRAINT foobar CHECK (true)
);
-- fed to 7.4, then \d
...
Check constraints:
"foobar" CHECK ()
-- note the empty parentheses!
-- mirroring the database caused:
ERROR: syntax error at or near ")" at character xxx
-- recreated table (actually, readded constraint) to 7.4, then \d
...
Check constraints:
"foobar" CHECK (true OR bar=1)
Szűcs Gábor wrote:
# create table foo (bar int, constraint foobar check (true));
CREATE TABLE
# \d foo
Table "public.foo"
Column | Type | Modifiers
--------+---------+-----------
bar | integer |
Check constraints:
"foobar" CHECK ()
Yeah, I can repro this with current REL7_4_STABLE sources, but it looks
fixed in HEAD and REL8_0_STABLE.
-Neil
Neil Conway <neilc@samurai.com> writes:
Szűcs Gábor wrote:
Check constraints:
"foobar" CHECK ()
Yeah, I can repro this with current REL7_4_STABLE sources, but it looks
fixed in HEAD and REL8_0_STABLE.
I think the reason is that 7.4 applies make_ands_implicit before storing
the constraint, while 8.0 and up don't. I'm inclined to think it's not
worth trying to fix in the back branches.
regards, tom lane
I agree it's not worth the effort, just found it "interesting" (duh)
and hastily sent a bugreport before checking upstream.
[off]
Another interesting story was 7.3 silently discarding unneeded
typecasts: create a view with a field ('a' || 'b')::varchar. The same
definition worked in 7.3 and 7.4 (both created a varchar field), but
7.3 dropped the unneeded typecast, and when dumping from 7.3 to 7.4
all these fields became text. I think 7.3 was simply "too smart for
our dumb problems" :)
[/off]
On 5/20/05, Tom Lane <tgl@sss.pgh.pa.us> wrote:
Neil Conway <neilc@samurai.com> writes:
Szűcs Gábor wrote:
Check constraints:
"foobar" CHECK ()Yeah, I can repro this with current REL7_4_STABLE sources, but it looks
fixed in HEAD and REL8_0_STABLE.I think the reason is that 7.4 applies make_ands_implicit before storing
the constraint, while 8.0 and up don't. I'm inclined to think it's not
worth trying to fix in the back branches.regards, tom lane
--
G.