On Wed, Sep 7, 2022 at 8:05 AM Simon Riggs <simon.riggs@enterprisedb.com> wrote:
>
> On Tue, 6 Sept 2022 at 21:33, Justin Pryzby <pryzby@telsasoft.com> wrote:
> >
> > On Tue, Sep 06, 2022 at 04:16:02PM +0100, Simon Riggs wrote:
> > > New chapter on transaction management, plus a few related changes.
> > >
> > > Markup and links are not polished yet, so please comment initially on
> > > the topics, descriptions and wording.
> >
> I've also added further notes about prepared transactions.
>
> I attach a diff against the original patch, plus a new clean copy.
>
Some feedback on the v4 patch, hopefully useful.
+<para>
+Transactions may be started explicitly using BEGIN and COMMIT
commands, known as
+a transaction block. A transaction will also be started and ended
implicitly for
+each request when outside of a transaction block.
+</para>
Transactions may be managed explicitly using BEGIN and COMMIT commands, known as
a transaction block.
+Committed subtransactions are recorded as committed if the main transaction
+commits. The word subtransaction is often abbreviated to "subxact".
+</para>
Committed subtransactions are only recorded as committed if the main
transaction commits,
otherwise any work done in a subtransaction will be rolled back or
aborted. The word subtransaction is
often abbreviated as "subxact".
+<para>
+Subtransactions may be started explicitly by using the SAVEPOINT
command, but may
+also be started in other ways, such as PL/pgSQL's EXCEPTION clause.
PL/Python and
+PL/TCL also support explicit subtransactions. Working with the C API, users may
+also call BeginInternalSubTransaction().
+</para>
I think this paragraph (or something similar) should be the opening
paragraph for this section, so that readers are immediately given
context for what PostgreSQL considers to be a subtransaction.
+prepared transactions that were prepared before the last checkpoint.
In the typical
+case, shorter-lived prepared transactions are stored only in shared
memory and WAL.
+Currently-prepared transactions can be inspected using the
pg_prepared_xacts view.
+</para>
Transactions that are currently prepared can be inspected using the
pg_prepated_xacts view.
* I thought the hyphenated wording looked odd, though I understand why
you used it. We don't use it elsewhere though (just `currently
prepared` san hyphen) so re-worded to match the other wording.
Robert Treat
https://xzilla.net
