Re: Adding REPACK [concurrently]

Robert Treat <rob(at)xzilla(dot)net> wrote:

> On Tue, Nov 4, 2025 at 9:48 PM jian he <jian(dot)universality(at)gmail(dot)com> wrote:

> > what the expectation of
> > pg_repackdb --index=index_name, the doc is not very helpful.
> >
> > pg_repackdb --analyze --index=zz --verbose
> > pg_repackdb: repacking database "src3"
> > pg_repackdb: error: processing of database "src3" failed: ERROR: "zz"
> > is not an index for table "tenk1"
> >
> > select pg_get_indexdef ('zz'::regclass);
> > pg_get_indexdef
> > ---------------------------------------------------
> > CREATE INDEX zz ON public.tenk2 USING btree (two)
> >
>
> Hmm... yes, this is a bit confusing. I didn't verify it in the code,
> but from memory I think the --index option is meant to be used only in
> conjunction with --table, in which case it would repack the table
> using the specified index. I could be overlooking something though.

The corresponding code is:

+ /*
+ * In REPACK mode, if the 'using_index' option was given but no index
+ * name, filter only tables that have an index with indisclustered set.
+ * (If an index name is given, we trust the user to pass a reasonable list
+ * of tables.)
+ *
+ * XXX it may be worth printing an error if an index name is given with no
+ * list of tables.
+ */
+ if (vacopts->mode == MODE_REPACK &&
+ vacopts->using_index && !vacopts->indexname)
+ {
+ appendPQExpBufferStr(&catalog_query,
+ " AND EXISTS (SELECT 1 FROM pg_catalog.pg_index\n"
+ " WHERE indrelid = c.oid AND indisclustered)\n");
+ }

I'm not sure if it's worth allowing the --index option to have an
argument. Since the user can specify multiple tables, he should also be able
to specify multiple indexes. And then the question would be: what should
happen if the user forgot to specify (or just mistyped) the index name for a
table which does not yet have the clustering index set? Skip that table (and
print out a warning)? Or consider it an error?

--
Antonin Houska
Web: https://www.cybertec-postgresql.com