Re: [HACKERS] Partition-wise aggregation/grouping

On Fri, Dec 1, 2017 at 7:41 AM, Ashutosh Bapat
<ashutosh(dot)bapat(at)enterprisedb(dot)com> wrote:
> This code creates plans where there are multiple Gather nodes under an Append
> node.

We should avoid that. Starting and stopping workers is inefficient,
and precludes things like turning the Append into a Parallel Append.

> AFAIU, the workers assigned to one gather node can be reused until that
> Gather node finishes. Having multiple Gather nodes under an Append mean that
> every worker will be idle from the time that worker finishes the work till the
> last worker finishes the work.

No, workers will exit as soon as they finish. They don't hang around idle.

> index b422050..1941468 100644
> --- a/src/tools/pgindent/typedefs.list
> +++ b/src/tools/pgindent/typedefs.list
> @@ -2345,6 +2345,7 @@ UnlistenStmt
> UnresolvedTup
> UnresolvedTupData
> UpdateStmt
> +UpperPathExtraData
> UpperRelationKind
> UpperUniquePath
> UserAuth
>
> Do we commit this file as part of the feature?

Andres and I regularly commit such changes; Tom rejects them.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company