Re: pg_rewind WAL segments deletion pitfall

Hmm. Doesn't it work to ignoring tli then? All segments that their
segment number is equal to or larger than the checkpoint locaiton are
preserved regardless of TLI?

> Also, we need to take into account the divergency LSN. Files after it are
> not required.

They are removed at the later checkpoints. But also we can remove
segments that are out of the range between the last common checkpoint
and divergence point ignoring TLI. 

the divergence point is also
compared?

> if (file_segno >= last_common_checkpoint_seg &&
>     file_segno <= divergence_seg)
>     <PRESERVE IT>;