When I configured a cascaded standby (i.e, made the additional standby server connect to the standby), I got the following errors, and a cascaded standby didn't start replication.
ERROR: timeline 0 of the primary does not match recovery target timeline 1
I didn't care about that case so far. To avoid a confusing error message, we should forbid a startup of walsender during recovery, and emit a suitable message? Or support such cascade-configuration? Though I don't think that the latter is difficult to be implemented, ISTM it's not the time to do that now.
-- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center