Still trying to find my way around the source code…
The file xact.c contains references to sub-transactions (subxact) and transaction nesting level, but no obvious documentation about what these correspond to in SQL. A search shows that plpython supports something called “proper sub transactions”. There are random mentions of subtransactions in the release notes, but nothing substantive that I can find, and nothing about transaction nesting.
Any pointers to docs or help to understand much appreciated.
Regards
David M Bennett FACS
Andl - A New Database Language - andl.org