On Mon, May 2, 2016 at 12:24 PM, <da...@andl.org> wrote: > 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.
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 -- Thomas Munro http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers