Avoid deleting critical WAL segments during pg_rewind Previously, in unlucky cases, it was possible for pg_rewind to remove certain WAL segments from the rewound demoted primary. In particular this happens if those files have been marked for archival (i.e., their .ready files were created) but not yet archived; the newly promoted node no longer has such files because of them having been recycled, but they are likely critical for recovery in the demoted node. If pg_rewind removes them, recovery is not possible anymore.
Fix this by maintaining a hash table of files in this situation in the scan that looks for a checkpoint, which the decide_file_actions phase can consult so that it knows to preserve them. Backpatch to 14. The problem also exists in 13, but that branch was not blessed with commit eb00f1d4bf96, so this patch is difficult to apply there. Users of older releases will just have to continue to be extra careful when rewinding. Co-authored-by: Полина Бунгина (Polina Bungina) <bung...@gmail.com> Co-authored-by: Alexander Kukushkin <cyberd...@gmail.com> Reviewed-by: Kyotaro Horiguchi <horikyota....@gmail.com> Reviewed-by: Atsushi Torikoshi <torikos...@oss.nttdata.com> Discussion: https://postgr.es/m/caatgl4ahzmbrsesaddz7065t+k+bscnadftqp1ncpmsqwa5...@mail.gmail.com Branch ------ REL_17_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/cb844d66b5872782481deebc793919c7d531c032 Modified Files -------------- src/bin/pg_rewind/filemap.c | 84 ++++++++++++++++++++++++--- src/bin/pg_rewind/filemap.h | 3 + src/bin/pg_rewind/meson.build | 1 + src/bin/pg_rewind/parsexlog.c | 21 +++++++ src/bin/pg_rewind/pg_rewind.c | 3 + src/bin/pg_rewind/t/010_keep_recycled_wals.pl | 62 ++++++++++++++++++++ src/tools/pgindent/typedefs.list | 2 + 7 files changed, 169 insertions(+), 7 deletions(-)
