Hi,
I'm new to Bucardo and like it so far. I have however a question about
the consistency of foreign keys. Consider these two simple tables with
master/master replication (Bucardo 5 / Psql 9.1):
create table parent (
id serial,
name text,
primary key (id)
);
create table child (
id serial,
name text,
parent int,
foreign key (parent) references parent(id) on delete cascade,
primary key (id)
);
After adding a row to each table the database looks like this:
foo=> select * from parent;
id | name
----+------
1 | p
(1 row)
foo=> select * from child;
id | name | parent
----+------+--------
1 | c | 1
(1 row)
Now in one database ('foo') I delete the parent row, and then
immediately (before replication kicks in) update the child in the other
database ('bar'):
foo=> delete from parent where id = 1;
DELETE 1
foo=> \c bar
You are now connected to database "bar" as user "dba".
bar=> update child set name = 'newc' where id = 1;
UPDATE 1
After Bucardo finishes replication the child row still exists, because
the conflict strategy is set to 'latest'. This is the result (in both
databases):
bar=> select * from parent;
id | name
----+------
(0 rows)
bar=> select * from child;
id | name | parent
----+------+--------
1 | newc | 1
(1 row)
The database is no longer consistent, the foreign key constraint is
violated since the parent has been deleted.
Is there any way to avoid / resolve this type of inconsistency?
Kind regards,
--
Hans van der Riet
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