> 2. Unlike "pg_wal", the "log" directory is not necessarily located inside PGDATA. The actual value is configured using "log_directory" GUC, which just happened to be "log" by default. And in fact actual values on source and target could be different.
I think we only care about files/dirs inside the datadir. Anything outside is out of scope for pg_rewind AFAIU. We can only address the common case here. As mentioned in this comment:
* XXX: There is no backend function to get a symbolic link's target in * general, so if the admin has put any custom symbolic links in the data * directory, they won't be copied correctly.
That's exactly my point. Users are very creative.
On one node they could set log_directory to for example "pg_log" and on another one "my_log".
And they would be writing logs to $PGDATA/pg_log and $PGDATA/my_log respectively and they are both located inside datadir.
Lets assume that on the source we have "pg_log" and on the target we have "my_log" (they are configured using "log_directory" GUC).
When doing rewind in this case we want neither to remove the content of "my_log" on the target nor to copy content of "pg_log" from the source.
It couldn't be achieved just by introducing a static string "log". The "log_directory" GUC must be examined on both, source and target.
