From: | Jana <jana(dot)vasseru(at)gmail(dot)com> |
---|---|
To: | pgsql-novice(at)postgresql(dot)org |
Subject: | Re: Delete performance |
Date: | 2009-06-15 13:33:45 |
Message-ID: | op.uvkimjhng6o41l@truhlik |
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Lists: | pgsql-novice |
On Sun, 14 Jun 2009 18:12:50 +0200, Frank Bax <fbax(at)sympatico(dot)ca> wrote:
> Jana wrote:
>> Hello,
>> i have a table with about 250m records from which i want to delete
>> thoose not contained in other table. I used this SQL query:
>> DELETE FROM data_structures_items WHERE id_data_structure NOT IN (
>> SELECT id_structure FROM data_structures);
>
>
> DELETE FROM data_structures_items, data_structures WHERE
> data_structures_items.id_data_structure =
> data_structures.id_data_structure AND
> data_structures_items.id_data_structure IS NULL;
>
Thanks for answer, this however is not a valid syntax (at least according
to manual, and my 8.3)
version. What could be done is
DELETE FROM data_structures_items USING data_structures
WHERE
data_structures_items.id_data_structure=data_structures.id_structure
AND something
but the problem is in that "something". I cannot write
data_structures_items.id_data_structure =
data_structures.id_data_structure AND
data_structures_items.id_data_structure IS NULL;
because it a) doesn't make sense (column can't be null and equal to
something at the same time), b) doesn't select what i want (rows whoose
id_data_structure is NOT in the data_structures table, i'm pretty sure it
is a number ). I can't join tables in DELETE command, and i can't think of
a way doing it with WHERE
Regards,
Jana
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