On Sun, 2002-12-29 at 22:09, li li wrote:
> Hi,
> As we can see all tuples of a child table when scanning parent table,
> I'm confused about if that means there are two copies that are stored on
> disk, one is for child table, and the other for parent table? If so,
> I have to reconsider the size of my database.
When you select from the parent table, all rows in its children are also
selected unless you use the keyword ONLY.
So
SELECT * FROM parent;
will show all rows of parent and children. But
SELECT * FROM ONLY parent;
will show just the rows in the parent table.
--
Oliver Elphick Oliver.Elphick@lfix.co.uk
Isle of Wight, UK http://www.lfix.co.uk/oliver
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