Problem with nested query - Mailing list pgsql-general

Hello,

I have quite strange problem with nested query.

mails=> explain INSERT INTO member(email)
mails->         select distinct email
mails->                 FROM iaddress
mails->                 WHERE NOT EXISTS (
mails(>                         SELECT email
mails(>                                 FROM  member
mails(>                                 WHERE member.email=iaddress.email);
NOTICE:  QUERY PLAN:

Unique  (cost=1869591274.28..1869591274.28 rows=0 width=12)
  ->  Sort  (cost=1869591274.28..1869591274.28 rows=1 width=12)
        ->  Seq Scan on iaddress  (cost=0.00..1869591274.27 rows=1 width=12)
              SubPlan
                ->  Seq Scan on member  (cost=0.00..10226.27 rows=1 width=12)

EXPLAIN

As far as you can see it uses sequence scan for inner select. This is quite
strange as if I do this select with a constant it will use index scan:

mails=> explain SELECT email
mails->                                 FROM  member
mails->                                 WHERE member.email='test';
NOTICE:  QUERY PLAN:

Index Scan using ix_member_email on member  (cost=0.00..4.76 rows=1 width=12)

EXPLAIN

Additional data.

mails=> select count(*) from iaddress;
 count
-------
 58742
(1 row)

mails=> select count(*) from member;
 count
--------
 219648
(1 row)

There is an index member(email).
PostgreSQL 7.0.2.

Any ideas?

--
Sincerely Yours,
Denis Perchine

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