deletions on master table takes for ever...

Hi folks ,

can anyone explain why the deletions below take so much time.
the problem is none of the queries below is faast ?

1. explain delete from email_bank where exists (select domain from
t_bad_domains where domain= email_bank.domain);

NOTICE: QUERY PLAN:
Seq Scan on email_bank (cost=0.00..724279.53 rows=1009007 width=6)
SubPlan
-> Index Scan using t_bad_domains_domain on t_bad_domains
(cost=0.00..296.39 rows=424 width=12)
EXPLAIN

2. explain delete from email_bank where email_bank.domain=
t_bad_domains.domain ;
NOTICE: QUERY PLAN:

Nested Loop (cost=0.00..304423734.99 rows=427899689 width=30)
-> Seq Scan on email_bank (cost=0.00..19092.07 rows=1009007
width=18)
-> Index Scan using t_bad_domains_domain on t_bad_domains
(cost=0.00..296.39 rows=424 width=12)

EXPLAIN

also find the table descriptions below.

Also i would like to tell that the are 8 tables linked to the master
table
email_bank so every deletetion on email_bank is eight deletions.

do i need to create indexes on the slave tables also ?

and the m/c is Dual PIII 800 and SCSI and 1 GB

regds
mallah.

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tradein_clients=> \d email_bank
Table "email_bank"
Column | Type | Modifiers
----------+------------------------+----------------------------------------------------

email_id | integer | default
nextval('"email_bank_email_id_seq"'::text)
userid | integer | not null default 0
email | character varying(100) | not null
country | character varying(100) |
domain | character varying(100) | default ''
tld | character varying(100) | default ''
Indexes: email_bank_email_key
Unique keys: email_bank_email_id_key,
uniq_email_insencase
Triggers: RI_ConstraintTrigger_63438161,
RI_ConstraintTrigger_63438159,
RI_ConstraintTrigger_63438157,
RI_ConstraintTrigger_63438155,
RI_ConstraintTrigger_63438153,
RI_ConstraintTrigger_63438151,
RI_ConstraintTrigger_63438149,
RI_ConstraintTrigger_63438147

tradein_clients=>

tradein_clients=> \d t_bad_domains
Table "t_bad_domains"
Column | Type | Modifiers
--------+------+-----------
domain | text |
Indexes: t_bad_domains_domain

tradein_clients=>
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