Subject Re: [IBO] TIBO: IndexFieldNames and empty column
Author Jason Wharton
The next sub-release will contain an improved algorithm for the horizontal
dataset refinement feature for TIBOTable. I only do HDR for those columns
which have a descending index defined to service them. If there is no
descending index then it will do the regular single cursor buffer instead of
the dual cursor buffer. Anyway, this improvement allows your database design
to have more of a deliberate influence on how the TIBOTable component
behaves. This is exactly the same as the TTable worked as well.

It is a rule of thumb that NULL's need to be suppressed from your data in
the circumstance where you are ordering your dataset by those columns. This
is because there isn't a way to optimize a query that involves a <, >
operator OR IS NULL for a column. I suppose I could maintain an additional
cursor that would merge in just records whose columns are NULL... InterBase
always puts NULL values at the end of the dataset whether ascending or

I don't know what the issue with the records disappearing are. I believe I
need more details.

Jason Wharton

----- Original Message -----
From: "Enrico Raviglione" <e.raviglione@...>
To: <>
Sent: Friday, March 08, 2002 11:40 AM
Subject: [IBO] TIBO: IndexFieldNames and empty column

> Hi,
> i have a TIBOTable displayed into a DBGrid, i can change the order of my
> data cliccking on the grid column title (like native TIB_GRID do).
> One of this column have some record = NULL.
> If i set the ordering on that column all the records with value=NULL are
> displayed (like the SELECT have a WHERE column NOT NULL clause).
> Anhoter problem are:
> If i set the descending order on that column then i go to the end of the
> file (using the navigator >> button) all the contens of the grid disappear
> like an empty table.
> If i order the same column in ascending order i can go to First or Last
> record and i can alwias see my table data (not the record with
> The TIBOTable have AutoFetchAll = false;
> If Autofetch is true all work fine (but are to much expensive in time
> setting this for all Table/Query).
> Regards,
> Enrico Raviglione.