pg_rewind fails on Windows where tablespaces are used

Chris Travers <chris.travers@stormatics.tech>

From: Chris Travers <chris.travers@stormatics.tech>

To: Farooq Rashed <farooq.rashed@desc.gov.ae>, pgsql-bugs@lists.postgresql.org

Date: 2024-05-08T08:02:21Z

Lists: pgsql-bugs

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

Fix readlink() for non-PostgreSQL junction points on Windows.
- 2c4a532c96a9 13.19 landed
- f4fd5325cc87 14.16 landed
- 9b136b0f2e53 15.11 landed
Fix stat() for recursive junction points on Windows.
- fbf8efbda88c 13.19 landed
- 9f1c67488e59 14.16 landed
- e708f31881fd 15.11 landed
Fix pg_rewind with in-place tablespaces when source is remote
- bf227926d22b 17.0 cited
Make unlink() work for junction points on Windows.
- f357233c9db8 16.0 cited
Use in-place tablespaces in regression test.
- d6d317dbf615 15.0 cited

Hi,

Setup is PostgreSQL on Windows with a tablespace on a separate drive.  When
I go to run pg_rewind it consistently fails with the following error:

pg_rewind: servers diverged at WAL location 39B/7EC6F60 on timeline 2
pg_rewind: rewinding from last common checkpoint at 39B/7E8E3F8 on timeline
2
pg_rewind: error: file "pg_tblspc/34244696" is of different type in source
and target

The file is confirmed to be a JUNCTION to the correct location on both the
source and target.  So the error looks like a problem interacting with
Windows and detecting JUNCTION types in this case.

I came across the following which looks like it would fix this problem but
don't have a proper build environment.  Please consider backporting the fix
at least as far as Postgres 15 as this bug fix does apply to non-in-place
tablespaces on Windows.  The thread is
https://postgrespro.com/list/thread-id/2657122

Best Regards,
Chris Travers