Re: New docs chapter on Transaction Management and related changes

On Wed, Nov 23, 2022 at 02:17:19AM -0600, Justin Pryzby wrote:
> On Tue, Nov 22, 2022 at 01:50:36PM -0500, Bruce Momjian wrote:
> > +
> > + <para>
> > + A more complex example with multiple nested subtransactions:
> > +<programlisting>
> > +BEGIN;
> > + INSERT INTO table1 VALUES (1);
> > + SAVEPOINT sp1;
> > + INSERT INTO table1 VALUES (2);
> > + SAVEPOINT sp2;
> > + INSERT INTO table1 VALUES (3);
> > + RELEASE SAVEPOINT sp2;
> > + INSERT INTO table1 VALUES (4))); -- generates an error
> > +</programlisting>
> > + In this example, the application requests the release of the savepoint
> > + <literal>sp2</literal>, which inserted 3. This changes the insert's
> > + transaction context to <literal>sp1</literal>. When the statement
> > + attempting to insert value 4 generates an error, the insertion of 2 and
> > + 4 are lost because they are in the same, now-rolled back savepoint,
> > + and value 3 is in the same transaction context. The application can
> > + now only choose one of these two commands, since all other commands
> > + will be ignored with a warning:
> > +<programlisting>
> > + ROLLBACK;
> > + ROLLBACK TO SAVEPOINT sp1;
> > +</programlisting>
> > + Choosing <command>ROLLBACK</command> will abort everything, including
> > + value 1, whereas <command>ROLLBACK TO SAVEPOINT sp1</command> will retain
> > + value 1 and allow the transaction to continue.
> > + </para>
>
> This mentions a warning, but what happens is actually an error:
>
> postgres=!# select;
> ERROR: current transaction is aborted, commands ignored until end of transaction block

Good point, new text:

The application can now only choose one of these two commands,
since all other commands will be ignored:

Updated patch attached.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson