> there us a "rec_version" and "no_rec_version"
> what is the default and what is usefull "no_rec_version" for?

* It is good practice to specify settings even if they are the same
as default ones. Then you do not have to care about what the default is,
and the code is more clear/readable/safe.

* The "rec_version" and "no_rec_version" can be used only with
"read_committed" isolation level. The default one is "no_rec_version".

* If you use "read_committed" transaction, always specify "rec_version".
The "no_rec_version" would only cause lots of "update conflict" exceptions
(the cases when "no_rec_version" can be useful are very very rare
and very very specific).

Ivan