Nothing is to be gained from using pgrepack outside of REPACK
(CONCURRENTLY), and it leads to assertion failures in assertion-enabled
builds, and to crashes due to bogus memory lifetime in production
builds. Reject attempts to do that with a clean error report.
Clean up the nearby code a tad while at it. The only functional changes
in that are that the output_writer_private context is allocated and
partially filled by the pgrepack output plugin; and that ->relid therein
is now always present (rather than only in assertion-enabled builds).
Other than that it's just minor code rearrangement and added comments.
Author: Álvaro Herrera <alvherre@kurilemu.de>
Reported-by: Nikita Kalinin <n.kalinin@postgrespro.ru>
Suggested-by: Zhijie Hou <houzj.fnst@fujitsu.com>
Reviewed-by: Antonin Houska <ah@cybertec.at> (older version)
Reviewed-by: Srinath Reddy Sadipiralla <srinath2133@gmail.com> (older version)
Discussion: https://postgr.es/m/19500-38a02529a69353a5@postgresql.org
Álvaro Herrera