Horton

Re: Add index scan progress to pg_stat_progress_vacuum

Sami Imseih <simseih@amazon.com>

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From: "Imseih (AWS), Sami" <simseih@amazon.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Nathan Bossart <nathandbossart@gmail.com>, Peter Geoghegan <pg@bowt.ie>, "Bossart, Nathan" <bossartn@amazon.com>, Justin Pryzby <pryzby@telsasoft.com>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>, "Masahiko Sawada" <sawada.mshk@gmail.com>
Date: 2022-04-06T21:22:38Z
Lists: pgsql-hackers 
>    At the beginning of a parallel operation, we allocate a chunk of>
>    dynamic shared memory which persists even after some or all workers
>    have exited. It's only torn down at the end of the parallel operation.
>    That seems like the appropriate place to be storing any kind of data
>    that needs to be propagated between parallel workers. The current
>    patch uses the main shared memory segment, which seems unacceptable to
>    me.

Correct, DSM does track shared data. However only participating
processes in the parallel vacuum can attach and lookup this data.

The purpose of the main shared memory is to allow a process that
Is querying the progress views to retrieve the information.

Regards,

Sami Imseih
Amazon Web Services

Commits

  1. Report index vacuum progress.

  2. Add new parallel message type to progress reporting.

  3. Remove MaxBackends variable in favor of GetMaxBackends() function.