You're not changing the length of an ST_GEOMETRY, you're changing the display size of
numeric column in a table (which happens to contain a geometry column).
The supported mechanism to doing database design changes is to backup the table, drop
the table, recreate the table (with the new layout), and repopulate the table (from backup,
if possible). I use this nearly exclusively.
It may also be possible to use SQL to alter the table (if it's not versioned), then use 'sdetable
-o describe' (as the owner) to convince ArcSDE to re-evaluate the table contents.
Finally, the unsupported mechanisms involve hacking the column registry table and/or the
geodatabase XML. I *never* mess with the XML, since a simple mistake can trash the entire
instance (though the same is true for etiher mechanism, which is why they're unsupported).
- V
