Horton

Re: [HACKERS] Parallel Append implementation

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Thomas Munro <thomas.munro@enterprisedb.com>
Cc: Adrien Nayrat <adrien.nayrat@anayrat.info>, Amit Khandekar <amitdkhan.pg@gmail.com>, amul sul <sulamul@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2018-07-30T17:05:43Z
Lists: pgsql-hackers

Attachments

On Sun, Jul 29, 2018 at 5:49 PM, Thomas Munro
<thomas.munro@enterprisedb.com> wrote:
> On Thu, May 10, 2018 at 7:08 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>>  [parallel-append-doc-v2.patch]
>
> +    plans just as they can in any other plan.  However, in a parallel plan,
> +    it is also possible that the planner may choose to substitute a
> +    <literal>Parallel Append</literal> node.
>
> Maybe drop "it is also possible that "?  It seems a bit unnecessary
> and sounds a bit odd followed by "may <verb>", but maybe it's just me.

Changed.

> +    Also, unlike a regular <literal>Append</literal> node, which can only have
> +    partial children when used within a parallel plan, <literal>Parallel
> +    Append</literal> node can have both partial and non-partial child plans.
>
> Missing "a" before "<literal>Parallel".

Fixed.

> +    Non-partial children will be scanned by only a single worker, since
>
> Are we using "worker" in a more general sense that possibly includes
> the leader?  Hmm, yes, other text on this page does that too.  Ho hum.

Tried to be more careful about this.

New version attached.

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

Commits

  1. Update parallel.sgml for Parallel Append

  2. Support Parallel Append plan nodes.

  3. Remove BufFile's isTemp flag.

  4. Improve comments for parallel executor estimation functions.

  5. Separate reinitialization of shared parallel-scan state from ExecReScan.

  6. Eat XIDs more efficiently in recovery TAP test.

  7. Avoid syntax error on platforms that have neither LOCALE_T nor ICU.

  8. Preparatory refactoring for parallel merge join support.