I made another patch for that.
I don't have much confidence with my English spelling so further
improvements may be needed.
If it is too much a change and potential regression, then I think that the
"and chain" variants should be consistent and just raise warnings.
We don't have an exact answer for implicit transaction chaining behavior
yet.
So I think it's better to disable this feature until someone discovers the
use cases for this.
Permitting AND CHAIN without a detailed specification might cause troubles
in future.
I think that it would be too bad to remove this feature for a small
implementation-dependent corner case.
Documentation says that COMMIT/ROLLBACK [AND CHAIN] apply to the "current
transaction", and "BEGIN initiates a transaction block".
If there is no BEGIN, there is no "current transaction", so basically the
behavior is unspecified, whether AND CHAIN or not, and we are free
somehow.
In such case, I'm simply arguing for consistency: whatever the behavior,
the chain and no chain variants should behave the same.
Now, I'd prefer error in all cases, no doubt about that, which might be
considered a regression. A way around that could be to have a GUC decide
between a strict behavior (error) and the old behavior (warning).
--
Fabien.
