Hi, On 2025-03-06 14:51:26 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2025-03-06 13:47:34 -0500, Tom Lane wrote: > >> ... I wonder if we could just rip out pg_upgrade's support > >> for DB-level parallelism, which is not terribly pretty anyway, and > >> simply pass the -j switch straight to pg_dump and pg_restore. > > > I don't think that'd work well, right now pg_dump only handles a single > > database (pg_dumpall doesn't yet support -Fc) *and* pg_dump is still serial > > for the bulk of the work that pg_upgrade cares about. > > I think the only parallelism that'd actually happen for pg_upgrade would be > > dumping of large objects? > > Uh ... the entire point here is that we'd be trying to parallelize its > dumping of stats, no? Most DBs will have enough of those to be > interesting, I should think.
Well, we added concurrent-pg-dump runs to pg_upgrade for a reason, presumably. Before stats got dumped, there wasn't any benefit of pg_dump level parallelism, unless large objects are used. Presumably we validated that there *is* gain from running pg_dump on multiple databases concurrently. There are many systems with hundreds of databases, removing all parallelism for those from pg_upgrade would likely hurt way more than what we can gain here. Greetings, Andres Freund
