At 10:12 PM 25/02/2004 +0100, you wrote:

>I have a query where one field is a blob - different documents saved in
>binary form.
>The blobfield is marked as non visible in the fielddefinition of the
>query, only fields like the
>filedate and size of the saved document are shown in a grid. My first
>question is: Does the blob go
>over the wire if only the grid is shown. Or is it only extracted from the
>database when it is really
>needed.

If it is not in the SELECT specification then it is not in the output.

>My second question is about the "size" of the blob when defining the field
>upon creation of the database. Is is necessary to carefully set this value
>to a certain value. If so, how do I calculate it.

No, for dynamic applications (like IBO) just ignore it. It will default to
80 but the API will ignore that as well, and segment the stream by its own
rules (which I think has something to do with packet size on the
network...). Once it arrives at the server, then the *server* makes its
own decisions about how many bytes to store in a segment, based on "page
ecology".

It's only needed for ESQL where you actually have to manipulate segments
yourself in the host code. (So it's only worth setting it if someone is
going to write ESQL applications for your database - but then that person
would need to decide on a segment size <g>).

fwiw, the default segment size was set at 80 because it is the size of one
line of output from a Unix text terminal - the qwerty phenomenon! <g>

Helen