Re: [PoC] pg_upgrade: allow to upgrade publisher node

On Thu, Oct 26, 2023 at 8:11 PM Zhijie Hou (Fujitsu)
<houzj(dot)fnst(at)fujitsu(dot)com> wrote:
>
> The BF animal fairywren[1] failed when testing
> 003_upgrade_logical_replication_slots.pl.
>
> From the log, I can see pg_upgrade failed to open the
> invalid_logical_replication_slots.txt:
>
> # Checking for valid logical replication slots
> # could not open file "C:/tools/nmsys64/home/pgrunner/bf/root/HEAD/pgsql.build/testrun/pg_upgrade/003_upgrade_logical_replication_slots/data/t_003_upgrade_logical_replication_slots_new_publisher_data/pgdata/pg_upgrade_output.d/20231026T112558.309/invalid_logical_replication_slots.txt": No such file or directory
> # Failure, exiting
>
> The reason could be the length of this path(262) exceed the windows path
> limit(260 IIRC). If so, I recall we fixed similar things before (e213de8e7) by
> reducing the path somehow.

Nice catch. Windows docs say that the file/directory path name can't
exceed MAX_PATH, which is defined as 260 characters. However, one must
opt-in to enable longer path names -
https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry
and https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation?tabs=registry#enable-long-paths-in-windows-10-version-1607-and-later.

> In this case, I think one approach is to reduce the file and testname to
> xxx_logical_slots instead of xxx_logical_replication_slots. But we will analyze more
> and share fix soon.
>
> [1] https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=fairywren&dt=2023-10-26%2009%3A04%3A54

+1 for s/003_upgrade_logical_replication_slots.pl/003_upgrade_logical_slots.pl
and s/invalid_logical_replication_slots.txt/invalid_logical_slots.txt.
In fact, we've used "logical slots" instead of "logical replication
slots" in the docs to be generic. By looking at the generated
directory path name, I think we can use shorter node names - instead
of old_publisher, new_publisher, subscriber - either use node1 (for
old publisher), node2 (for subscriber), node3 (for new publisher) or
use alpha (for old publisher), bravo (for subscriber), charlie (for
new publisher) or such shorter names. We don't have to be that
descriptive and long in node names, one can look at the test file to
know which one is what.

--
Bharath Rupireddy
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com