Re: New docs chapter on Transaction Management and related changes

On Wed, Nov 9, 2022 at 09:16:18AM -0500, Robert Treat wrote:
> > "Subtransactions of the named savepoint" is somewhat confusing; how about
> > "subtransactions of the subtransaction established by the named savepoint"?
> >
> > If that is too long and explicit, perhaps "subtransactions of that subtransaction".
> >
>
> Personally, I think these are more confusing.

That text is gone.

> > > --- a/doc/src/sgml/ref/rollback.sgml
> > > +++ b/doc/src/sgml/ref/rollback.sgml
> > > @@ -56,11 +56,14 @@ ROLLBACK [ WORK | TRANSACTION ] [ AND [ NO ] CHAIN ]
> > > <term><literal>AND CHAIN</literal></term>
> > > <listitem>
> > > <para>
> > > - If <literal>AND CHAIN</literal> is specified, a new transaction is
> > > + If <literal>AND CHAIN</literal> is specified, a new unaborted transaction is
> > > immediately started with the same transaction characteristics (see <xref
> > > linkend="sql-set-transaction"/>) as the just finished one. Otherwise,
> > > no new transaction is started.
> >
> > I don't think that is an improvement. "Unaborted" is an un-word. A new transaction
> > is always "unaborted", isn't it?
> >
>
> I thought about this as well when reviewing it, but I do think
> something is needed for the case where you have a transaction which
> has suffered an error and then you issue "rollback and chain"; if you
> just say "a new transaction is immediately started with the same
> transaction characteristics" it might imply to some the new
> transaction has some kind of carry over of the previous broken
> transaction... the use of the word unaborted makes it clear that the
> new transaction is 100% functional.

I changed it to:

a new (unaborted) transaction is immediately started

> ISTR that you only use a comma before since in cases where the
> preceding thought contains a negative.
>
> In any case, are you thinking something like this:
>
> " 64 open subxids are cached in shared memory for each backend; after
> that point the overhead increases significantly due to additional disk I/O
> from looking up subxid entries in <filename>pg_subtrans</filename>."

I went with:

Up to 64 open subxids are cached in shared memory for
each backend; after that point, the storage I/O overhead increases
significantly due to additional lookups of subxid entries in
<filename>pg_subtrans</filename>.

New 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