> I am using isql.exe locally, feeding SQL-operators through the
> clipboard. Of course, the script does not contain substring(), just
> "update cms_wiki set u_text = text;" and it hangs eating resources.
> Single-record operator "update cms_wiki set u_text = text where id =
> 15;" hangs also, without any exceptions, i.e. Firebird is eating CPU and
> doing writes to HDD for a very long time (till I kill'em all to make the
> computer usable again).
> So I suspect some implicit limitation there, even without substring().

Reproducible bug report will be very appreciated.

Feel free to fill it at http://tracker.firebirdsql.org/

Regards,
Vlad