RE: Views and Indexes -- MIDRANGE-L

There's always the SQL Reference, but it takes digging to find things. I searched on "logical file" and got a little info.

There's Paul Conte's venerable book on DB2/400 - <www.iseries.ibm.com/db2> has links to a couple chapters of it at iSeries Network.

While digging around I found the following intriguing statement from the SQL Reference:

Adding a column has no cascaded effects to SQL views or most logical files. For example, adding a column to a table does not cause the column to be added to any dependent views, even if those views were created with a SELECT * clause.

So a SELECT *, which means all columns, is limited to the columns defined at the time the view was created. This is similar to the typical behavior of logicals that do not break if you add a column to the underlying physical.

Hmm!
Vern

At 08:14 AM 7/27/2004, you wrote:

> -----Original Message-----
> From: midrange-l-bounces@xxxxxxxxxxxx / Paul Tuohy
> Sent: Monday, July 26, 2004 6:58 PM
>
> But I think that a combined view/index would be the ideal solution. And it
> should be possible since it is already there in DDS.
>
> An SQL index is a keyed logical. i.e. there is an access path entry for
> every row.
> An SQL view is a non-keyed logical. i.e. there is no access path.
>
> If you define a DDS logical with Sequence (a key) and select/omit logic,
> then the access path only contains the rows that meet the selection
> criteria. i.e. selection criteria is checked when the row is
> inserted/updated. I want SQL to allow me do this!
> If you specify DYNSLT, then the access path contains all rows and the
> selection criteria is checked when the access path is read (which is what
> SQL Select does using a view and an index).
>
> Clear as mud :-)
>
> Paul

Doesn't it seem likely that someone somewhere wrote an article that compares
SQL & DDS "logicals"?  I looked briefly, but didn't find anything.  Anybody
have a useful reference?

tia,
db

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