Re: Adding REPACK [concurrently]

Hello,

Here's a second cut of the initial REPACK work. Antonin added an
implementation of pg_repackdb, and there's also a couple of bug fixes
that were reported in the thread. I also added support for the ANALYZE
option as noted by Robert Treat, though it only works if you specify a
single non-partitioned table. Adding for the multi-table case is likely
easy, but I didn't try.

I purposefully do not include the CONCURRENTLY work yet -- I want to get
this part commitable-clean first, then we can continue work on the
logical decoding work on top of that.

Note choice of shell command name: though all the other programs in
src/bin/scripts do not use the "pg_" prefix, this one does; we thought
it made no sense to follow the old programs as precedent because there
seems to be a lament for the lack of pg_ prefix in those, and we only
keep what they are because of their long history. This one has no
history.

Still on pg_repackdb, the implementation here is to install a symlink
called pg_repackdb which points to vacuumdb, and make the program behave
differently when called in this way. The amount of additional code for
this is relatively small, so I think this is a worthy technique --
assuming it works. If it doesn't, Antonin proposed a separate binary
that just calls some functions from vacuumdb. Or maybe we could have a
common source file that both utilities call.

I edited the docs a bit, limiting the exposure of CLUSTER and VACUUM
FULL, and instead redirecting the user to the REPACK docs. In the
REPACK docs I modified things for additional clarity.

--
Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/
"Selbst das größte Genie würde nicht weit kommen, wenn es
alles seinem eigenen Innern verdanken wollte." (Johann Wolfgang von Goethe)
Ni aún el genio más grande llegaría muy lejos si
quisiera sacarlo todo de su propio interior.