Re: pgsql: docs: fist draft version of the PG 12 release notes

On Fri, May 10, 2019 at 10:54:32AM +0900, Amit Langote wrote:
> On 2019/05/10 5:57, Bruce Momjian wrote:
> > So, in this case, there were so many partitioning improvements, I just
> > lumped them into one item. I think everyone can consider partitions to
> > perform much better in PG 12. Is there something more specific we
> > should communicate here?
>
> So the current text, which is:
>
> +<para>
> +Improve performance of pruning many partitions (Amit Langote, David
> Rowley, Tom Lane, Álvaro Herrera)
> +</para>
> +
> +<para>
> +Now thousands of partitions can be pruned efficiently.
> +</para>
> +</listitem>
>
> mentions improving "pruning" efficiency which applies only to
> SELECT/UPDATE/DELETE queries and can be attributed to only one of the many
> commits listed with this item. Performance of short INSERTs (as opposed
> to bulk-inserts including COPY) is also improved, but it has nothing to do
> "pruning".
>
> That said, efficiency is improved in both cases by not doing redundant
> work for partitions that are not affected by the query, that is,
>
> * for partitions which are pruned for a given SELECT/UPDATE/DELETE query
> (planner improvement)
>
> * for partitions which are not inserted into by a given INSERT statement
> (executor improvement, part of which was done in v11 but v11 still locks
> *all* partitions whereas v12 will only lock those that are inserted into)
>
>
> So, it might be fair to lump them, but maybe not use the word "pruning",
> because it describes only subset of affected workloads.

I struggled to talk about partitioning since there were so many
improvements. I favored a more generic item that just suggested
dramatic improvements. I have modified the text to:

Improve performance of many operations on partitioned tables (Amit
Langote, David Rowley, Tom Lane, Álvaro Herrera)

Also, thousands of partitions can now be pruned efficiently.

Committed. Does that work?

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

+ As you are, so once was I. As I am, so you will be. +
+ Ancient Roman grave inscription +