INHERIT

Oliver Elphick wrote:

Peter Harvey wrote:

If I try to get the columns from pg_attribute using the oid of a child
table created with INHERIT I get its columns AND all of its inherited
columns.

How do I just get the columns added by the child table?

I figure I could check each column to see if they also exist in
pg_attribute under a parent table but I figure there must be an
easier/faster way? Another pg_* table perhaps? Besides; I am not certian
this would work if there is a common column between a child and one of
its parents (if that is even allowed)?

hannu=# \d parent 
         Table "parent"
 Attribute |  Type   | Modifier 
-----------+---------+----------
 parid     | integer | not null
Index: parent_pkey

hannu=# create table badchild (parid text) inherits (parent);
NOTICE: CREATE TABLE: merging attribute "parid" with inherited
definition
ERROR: CREATE TABLE: attribute "parid" type conflict (int4 and text)
hannu=#

And anyway, in the current state I would advise you not to put too much
hope in postgreSQL's OO features, especially inheritance ;)

-------------
Hannu

Peter Harvey wrote:

If I try to get the columns from pg_attribute using the oid of a child
table created with INHERIT I get its columns AND all of its inherited
columns.

How do I just get the columns added by the child table?

I figure I could check each column to see if they also exist in
pg_attribute under a parent table but I figure there must be an
easier/faster way? Another pg_* table perhaps? Besides; I am not certian
this would work if there is a common column between a child and one of
its parents (if that is even allowed)?

As usual, any help would be greatly appreciated.

SELECT a.attname
FROM pg_attribute AS a,
pg_class AS c,
pg_inherits AS i
WHERE a.attrelid = c.oid AND
i.inhrelid = c.oid AND
c.relname = 'child_table'
AND a.attname NOT IN (
SELECT a.attname
FROM pg_attribute AS a,
pg_class AS c,
pg_inherits AS i
WHERE i.inhrelid = c.oid AND
a.attrelid = i.inhparent AND
c.relname = 'child_table'
)

--
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight http://www.lfix.co.uk/oliver
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