Make sure to do a rollback in case of errors in wrap_finish()

[jwarlander]

While integrating the query wrapper into one of our loading scripts, I noticed as I was testing the outcome that even if a wrapper:query(...) call failed, and aborted the script, previous database updates within the same script would still be committed.

This happens because wrap_query, in case of an error and where self.on_error == 'abort', calls self:finish(), which in the default implementation proceeds to just write the log entries and do a self:commit().

As this was somewhat surprising to me, I felt that perhaps wrap_finish should do a rollback before writing the log entries if there were any errors.

If one doesn't want a rollback to happen in case of errors, it's easy enough to set self.on_error to something else than abort, and handle errors manually.

Alternatively, one can also do some checkpointing by just calling wrapper:commit() at well-chosen places throughout a script, if there are partial changes that should be preserved.

[jwarlander]

Any comments, or obstacles for this change getting merged? :) If rollback on error isn't the wanted behavior, then that's fine, of course; just let me know!

[jwarlander]

Ping.. @ThomasBestfleisch, @exasol-szba, @exaValerieWiedemann :)

[exasol-szba]

Ping.. @ThomasBestfleisch, @exasol-szba, @exaValerieWiedemann :)

Hallo, hallo!
Sorry for not noticing your communication earlier; this was the first time GitHub notified me in relation to this thread.
I will look into this. I think that the whole logging part should be rewritten as there are other problems with it (although they are more cosmetic).

[jwarlander]

Hello!
No worries.. let me know if there's anything I can help out with :)

[jschildgen]

We added an option on_error = 'rollback' (same as abort, but does not commit but rollback in case of an error). This should fix your problem.