From: | Theo Kramer <theo(at)flame(dot)co(dot)za> |
---|---|
To: | pgsql-hackers(at)postgreSQL(dot)org |
Subject: | Re: [HACKERS] Slow - grindingly slow - query |
Date: | 1999-11-11 20:50:14 |
Message-ID: | 382B2C06.356F9234@flame.co.za |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
The Hermit Hacker wrote:
>
> What does:
>
> explain select domain from accountdetail
> where domain not in (
> select domain from accountmaster);
>
> show?
NOTICE: QUERY PLAN:
Seq Scan on accounts (cost=3667.89 rows=34958 width=12)
SubPlan
-> Seq Scan on accounts (cost=3667.89 rows=33373 width=12)
EXPLAIN
> Also, did you do a 'vacuum analyze' on the tables?
Yes - should have mentioned that.
> Also, how about if you get rid of the views
>
> SELECT domain FROM account
> WHERE registrationtype <> 'N';
>
> *shakes head* am I missing something here? I'm reading your SELECT and
> 'CREATE VIEW's and don't they negate each other? *scratch head*
No - a domain can both be new (registrationtype 'N') and updated
(registrationtype 'U') ie. one or more rows with the same domain with one row
containing a domain with registrationtype 'N' and zero or more rows containing
the same domain with registrationtype not 'N'. The reason for the <> 'N' and
not just = 'U' is that we have a couple of rows with registrationtype set to
something else.
> The subselect is saying give me all domains whose registration type = 'N'.
> The select itself is saying give me all domains whoe registration type <>
> 'N' (select accountdetail.domain from accountdetail), and narrow that
> listing down further to only include those domains whose registration type
> <> 'N'?
>
> Either I'm reading this *totally* wrong, or you satisfy that condition
> ujust by doing a 'SELECT domain FROM accountdetail;' ...
>
> No?
No :). See above
--------
Regards
Theo
From | Date | Subject | |
---|---|---|---|
Next Message | Frank Cusack | 1999-11-11 20:50:59 | Re: [HACKERS] Re: [BUGS] uniqueness not always correct |
Previous Message | Hannu Krosing | 1999-11-11 20:41:31 | Re: [HACKERS] Slow - grindingly slow - query |