Re: Very slow left outer join

On Tue, 29 May 2007 17:16:57 -0700, "Tyrrill, Ed" <tyrrill_ed(at)emc(dot)com> wrote:
> mdsdb=# explain analyze select backupobjects.record_id from
> backupobjects left outer join backup_location using(record_id) where
> backup_id = 1071;
[...]
>
> Here are the two tables in the query:
>
> mdsdb=# \d backup_location
> Table "public.backup_location"
> Column | Type | Modifiers
> -----------+---------+-----------
> record_id | bigint | not null
> backup_id | integer | not null
[...]
>
> mdsdb=# \d backupobjects
> Table "public.backupobjects"
> Column | Type | Modifiers
> ----------------+-----------------------------+-----------
> record_id | bigint | not null
> dir_record_id | integer |
> name | text |
> extension | character varying(64) |
> hash | character(40) |
> mtime | timestamp without time zone |
> size | bigint |
> user_id | integer |
> group_id | integer |
> meta_data_hash | character(40) |

Why are you using left join?

The where condition is going to force the row to exist.

klint.

+---------------------------------------+-----------------+
: Klint Gore : "Non rhyming :
: EMail : kg(at)kgb(dot)une(dot)edu(dot)au : slang - the :
: Snail : A.B.R.I. : possibilities :
: Mail University of New England : are useless" :
: Armidale NSW 2351 Australia : L.J.J. :
: Fax : +61 2 6772 5376 : :
+---------------------------------------+-----------------+