Re: VIEWS compared to Nodes as Windows into data

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"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c75rev$tdq$1_at_news.netins.net...
> Yes -- good --that might be the question I should ask -- if one creates a
> view that joins in table G and then Pat queries against this view and
> includes no columns from G, does the join get executed? I would think
that
> under certain conditions the join would be required, such as in the case
of
> an inner join where there would be more rows if the join were not
performed.

What do you mean by "performing the join" or "the join get executed" ? :-) When Pat query against G, she gets what she was asking for .

What atomic operations would be "executed" by the DBMS in the two scenarios/DBMSs you have in mind ?

Why there would be more operations for a RDBMS than for any other DBMS ? As I said "Relational" is just a language.

> But do current RDBMS's figure out when they don't need to include the join
> bz they know (how?) that the join will not result in a different row set
and
> there are no attributes from table G in the query against the view?

There is a current RDBMS ? :-)
If Pat asked for the join, an RDBMS would need to consider it. If Pat haven't asked for a field from table G, then an important part of the join may be skipped.
Sometime the other part of the join can be skipped too. ;-)

It is called query optimization.

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