Re: pg_dump --load-via-partition-root vs. parallel restore

On Tue, Aug 28, 2018 at 3:53 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Parallel pg_restore generally assumes that the archive file is telling it
> the truth about data dependencies; in particular, that a TABLE DATA item
> naming a particular target table is loading data into exactly that table.
> --load-via-partition-root creates a significant probability that that
> assumption is wrong, at least in scenarios where the data really does get
> redirected into other partitions than the original one. This can result
> in inefficiencies (e.g., index rebuild started before a table's data is
> really all loaded) or outright failures (foreign keys or RLS policies
> applied before the data is all loaded). I suspect that deadlock failures
> during restore are also possible, since identify_locking_dependencies
> is not going to be nearly close to the truth about which operations
> might hold which locks.

Hmm. I had the idea that this wasn't a problem because I thought we
had all of pg_dump strictly separated into pre-data, data, and
post-data; therefore, I thought it would be the case that none of that
other stuff would happen until all table data was loaded. From what
you are saying here, I guess that's not the case?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company