as those for inherited columns; that is, it's no longer allowed for a child
table to not have a check constraint matching one that exists on a parent.
This satisfies the principle of least surprise (rows selected from the parent
will always appear to meet its check constraints) and eliminates some
longstanding bogosity in pg_dump, which formerly had to guess about whether
check constraints were really inherited or not.
The implementation involves adding conislocal and coninhcount columns to
pg_constraint (paralleling attislocal and attinhcount in pg_attribute)
and refactoring various ALTER TABLE actions to be more like those for
columns.
Alex Hunsaker, Nikhil Sontakke, Tom Lane
alter table ac add constraint ac_check check (aa is not null);
CREATE TABLE bc (bb TEXT) INHERITS (ac);
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
ERROR: new row for relation "ac" violates check constraint "ac_check"
insert into bc (aa) values (NULL);
ERROR: new row for relation "bc" violates check constraint "ac_check"
alter table bc drop constraint ac_check; -- fail, disallowed
ERROR: cannot drop inherited constraint "ac_check" of relation "bc"
alter table ac drop constraint ac_check;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
ERROR: new row for relation "ac" violates check constraint "ac_aa_check"
insert into bc (aa) values (NULL);
ERROR: new row for relation "bc" violates check constraint "ac_aa_check"
alter table bc drop constraint ac_aa_check; -- fail, disallowed
ERROR: cannot drop inherited constraint "ac_aa_check" of relation "bc"
alter table ac drop constraint ac_aa_check;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
alter table ac add constraint ac_check check (aa is not null);
alter table bc no inherit ac;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
create table ac (a int constraint check_a check (a <> 0));
create table bc (a int constraint check_a check (a <> 0), b int constraint check_b check (b <> 0)) inherits (ac);
NOTICE: merging column "a" with inherited definition
NOTICE: merging constraint "check_a" with inherited definition
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc') order by 1,2;
create table ac (a int constraint check_a check (a <> 0));
create table bc (b int constraint check_b check (b <> 0));
create table cc (c int constraint check_c check (c <> 0)) inherits (ac, bc);
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc', 'cc') order by 1,2;
select pc.relname, pgc.conname, pgc.contype, pgc.conislocal, pgc.coninhcount, pgc.consrc from pg_class as pc inner join pg_constraint as pgc on (pgc.conrelid = pc.oid) where pc.relname in ('ac', 'bc', 'cc') order by 1,2;
Tom Lane
17 years ago