Re: speed up pg_upgrade with large number of tables

> On 5 Jul 2024, at 09:12, 杨伯宇(长堂) <yangboyu.yby@alibaba-inc.com> wrote:

> 1: Skip Compatibility Check In "pg_upgrade"
> =============================================
> Concisely, we've got several databases, each with a million-plus tables.
> Running the compatibility check before pg_dump can eat up like half an hour.
> If I have performed an online check before the actual upgrade, repeating it
> seems unnecessary and just adds to the downtime in many situations.
>
> So, I'm thinking, why not add a "--skip-check" option in pg_upgrade to skip it?
> See "1-Skip_Compatibility_Check_v1.patch".

How would a user know that nothing has changed in the cluster between running
the check and running the upgrade with a skipped check?  Considering how
complicated it is to understand exactly what pg_upgrade does it seems like
quite a large caliber footgun.

I would be much more interested in making the check phase go faster, and indeed
there is ongoing work in this area.  Since it sounds like you have a dev and
test environment with a big workload, testing those patches would be helpful.
https://commitfest.postgresql.org/48/4995/ is one that comes to mind.

--
Daniel Gustafsson