Frequency of archive_cleanup_command

[A J <s5aly@xxxxxxxxx>]

Couple of questions:

1. At what frequency is the archive_cleanup_command executed from the recovery.conf file on the standby ?

2. If for some reason lets say a WAL file is missing from the archive directory but the files after that are present. When the standby tries to restore the missing WAL file, does it fail or it simply skips the missing WAL file and goes to the next one.

Thanks.