> I have recently returned to the world of databases in general and
> informix in particular after a long abscence so apologies if this is
> not worded well. I have a client site which is using the informix time
> series datablade and creates their own tables deriving data from the
> tables containing time seies columns and one of these derived tables
> is causing us certain problems.
> I would like to know if there is a quick and easy way to establish
> whether one of these derived tables is a virtual table.
Contrary to other posts, a virtual table is not equivalent to a view.
It is listed in systables as tabtype 'T.' I don't know how you can
tell it is virtual, except maybe for it's size. For example, in
ServerStudioJE you can see the number of extents and size of extents
for a table (there are other methods, too). A virtual table created by
TimeSeries will have many thousands/millions of rows but actually take
very little space (1 small extent). Another clue is the presence of a
datetime year to fraction(5) field in the table. This is required in
the TimeSeries type of the "parent" table, so will always exist in the
virtual table. Virtual tables of other sorts (views into flat files,
etc.) may not work this way.
It acts sort of like a view, though you can insert and delete (not
update). As a convention, we name our virtual tables
originaltablename_virt to make them stand out. If you need more help
with this, I suggest joining the DataBlade list at www.iiug.org. Some
of the experts hang out there (and not here).
Sean R. Durity
novice TimeSeries user