Question

I’ve defined my tables so:

create table device (
id serial primary key,
manufacturerid integer references manufacturer(id) on delete restrict,
model text,
price real,
usagepros text,
usagecons text
);

create table robot (
numaxes integer,
capacity real,
reach real,
accuracy real,
installmethodid integer references installmethod(id) on delete restrict,
mass real
) inherits (device);

create table robotComplex(
id serial primary key,
name text
);

create table robotComplexDevice(
id serial primary key,
deviceId integer references device(id) on delete restrict,
robotcomplexid integer references robotcomplex(id) on delete cascade
);

etc...

I get the following when running sql commands:

 id  | manufacturerid | model | price | usagepros | usagecons | numaxes | capacity | reach | accuracy | installmethodid | mass  
-----+----------------+-------+-------+-----------+-----------+---------+----------+-------+----------+-----------------+-------
 159 |            117 | Robot | 100.3 | OK        | NoOK      |       6 |     15.3 |  15.4 |  76.1234 |              45 | 100.1

> select * from device; 
 id  | manufacturerid | model | price | usagepros | usagecons 
-----+----------------+-------+-------+-----------+-----------
 159 |            117 | Robot | 100.3 | OK        | NoOK

> select * from robotcomplex;
 id |     name     
----+--------------
 27 | Complex


> insert into robotcomplexdevice (deviceid, robotcomplexid) values (159, 27);
ERROR:  insert or update on table "robotcomplexdevice" violates foreign key constraint        "robotcomplexdevice_deviceid_fkey"
DETAIL:  Key (deviceid)=(159) is not present in table "device".

For some reason, even though I’ve defined the “robot” table to inherit “deivice” table, I can’t reference it. Maybe I don’t get object-relational database model correctly. But if you can’t reference the tables so then what is the point of object-relational model?

Answer 1

This is documented behaviour:

http://www.postgresql.org/docs/current/static/ddl-inherit.html#DDL-INHERIT-CAVEATS