Re: How to append tables in a view

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От Alban Hertroys
Тема Re: How to append tables in a view
Дата
Msg-id 45D1905F.1020107@magproductions.nl
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Ответ на Re: How to append tables in a view  ("Shoaib Mir" <shoaibmir@gmail.com>)
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Shoaib Mir wrote:
> So hmm a UNION with an ORDERY BY should be good for this scenario...

Only if the order matters to the OP, but he can always perform an ORDER
BY on the queries on his view. I don't really see the point.

The main difference between UNION and UINION ALL is that the latter
allows for duplicates, which removes the need to unduplicate the results
of the UNION (which requires ordering and is therefore relatively
expensive).

In short; if duplicates don't matter (or are desirtable even) UNION ALL
is faster.

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Alban Hertroys
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