I would use an outer join and check only those null-value records in the
right table with id's referencing table A
Sample query:
select a.*,b.* from a
left outer join b on a.id = b.a_id -- assuming a_id is my referencing
column to a
where b.id is null;
This will yield all columns in table a which has a null value on table b
This is just from the top of my head, just a concept, I might have some
syntax error.
-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Wes
Sent: Wednesday, January 11, 2006 11:51 PM
To: Postgresql-General
Subject: [GENERAL] Finding orphan records
I'm trying to find/delete all records in table A that are no longer
referenced by tables B or C. There are about 4 million records in table A,
and several hundred million in tables B and C.
Is there something more efficient than:
select address_key, address from addresses where ( not exists(select 1 from
B where BField=addresses.address_key limit 1) ) and ( not exists(select 1
from C where CField=addresses.address_key limit 1) )
Of course, all fields above are indexed.
There are foreign key references in B and C to A. Is there some way to
safely leverage that?
Wes
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