Re: PostgreSQL 12: Feature Highlights

On Wed, May 22, 2019 at 12:33:10PM +1200, David Rowley wrote:
> On Wed, 22 May 2019 at 02:55, Bruce Momjian <bruce@momjian.us> wrote:
> > This brings up a few points.  First, it seems the change affects
> > partitioned tables and UNION ALL, which means it probably needs to be
> > listed in two sections.   Second, is it only parallelism paths that are
> > added?  I am not sure if people care about a node being removed,
> > especially when the might not even know we do that step, but they do
> > care if there are new optimization possibilities.
> 
> Like Amit, I think the optimizer section is fine.  Another thing that
> is affected is that you may no longer get a Materialize node in the
> plan.  Previously you might have gotten something like Merge Join ->
> Materialize -> Append -> Seq Scan, now you might just get Merge Join
> -> Seq Scan.  This is because Append / MergeAppend don't support mark
> and restore. Removing them would allow the materialize node to be
> skipped in cases where the single subpath of the Append does support
> mark and restore.

How is this patch for the item?  I put it in the Optimizer section.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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