> From: Thomas Munro [mailto:thomas.mu...@enterprisedb.com]
> > 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. > > Subtransactions are used to implement SAVEPOINT, and also BEGIN blocks with > EXCEPTION clauses in plpgsql. > > http://www.postgresql.org/docs/9.5/static/sql-savepoint.html > http://www.postgresql.org/docs/9.5/static/plpgsql-control-structures.html#PLPGSQL-ERROR-TRAPPING Thanks. I guess that explains the nesting level too. It seems there is an internal API based on: * BeginInternalSubTransaction * RollbackAndReleaseCurrentSubTransaction * ReleaseCurrentSubTransaction This looks like something I shall need to use. I have the plandl language handler all working, and understanding the transaction environment is turning out to be a major challenge. Regards David M Bennett FACS Andl - A New Database Language - andl.org -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
