On Wed, Sep 7, 2022 at 8:05 AM Simon Riggs <simon.ri...@enterprisedb.com> wrote: > > On Tue, 6 Sept 2022 at 21:33, Justin Pryzby <pry...@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
