Hi Sergei, On Mon, Apr 5, 2021 at 8:04 PM Sergei Golubchik <s...@mariadb.org> wrote: > > Hi, Aleksey! > > On Feb 26, Aleksey Midenkov wrote: > > > > > > > > > > In other words, if one can create an arbitrary history by > > > > > manipulating @@timestamp variable, > > > > > @@system_versioning_insert_history allows to do it more > > > > > conveniently. But if one cannot - he cannot. > > > > > > > > Then do we need additional setting @@system_versioning_insert_history? > > > > Iff one can manipulate history via @@timestamp variable let him set > > > > row_start/row_end columns. > > > > > > Sure, that's possible. > > > > > > I just thought @@system_versioning_insert_history could be like an extra > > > safety (not security) measure. To prevent history from being modified > > > unintentionally. > > > > Well, unless one specified row_start/row_end explicitly he is safe. > > > > But, since we need to specify implicit system fields we cannot avoid > > adding one more session variable. In my current iteration I made > > @@force_fields_visible which is more straightforward in what it does: > > I'm sorry, I don't understand. > > First, visibility is pretty much unrelated concept. row_start/row_end > can be visible or invisible, and they can be writable or not writable - > those are orthogonal concepts.
To be able to specify them in INSERT command they must be at least user-invisible. System-invisible fields are ignored. > > And second, the name is wrong, there are no "fields" row_start and > row_end unless the user creates then explicitly. They are pieces of > metadata that every row has, something that Oracle, for example, calls > "pseudocolumns". Something like @@system_versioning_row_start_row_end_visible > would be more correct, but ugly. In fact, I'd say that > @@system_versioning_insert_history was the best one. I think you are complicating things where complication is not needed. Pseudo- or not they are fields. Besides, the variable is not about system versioning. It can make any system-invisible fields visible. > > Regards, > Sergei > VP of MariaDB Server Engineering > and secur...@mariadb.org -- All the best, Aleksey Midenkov @midenok _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
