Re: Performance issues during pg_restore -j with big partitioned table

Hello list.

My database includes one table with 1000 partitions, all of them rather
sizeable. I run:

   pg_restore -j12 --no-tablespaces --disable-triggers --exit-on-error --no-owner --no-privileges -n public -d newdb custom_format_dump.pgdump

Right now after 24h of restore, I notice weird behaviour, so I have
several questions about it:

+ 11 postgres backend processes are sleeping as "TRUNCATE TABLE waiting".
   I see that they are waiting to issue a TRUNCATE for one of the
   partitions and then COPY data to it.  Checking the log I see that
   several partitions have already been copied finished, but many more
   are left to start.

   Why is a TRUNCATE needed at the start of a partition's COPY phase? I
   didn't issue a --clean on the command line (I don't need it as my
   database is newly created), and I don't see a mention of related
   TRUNCATE in the pg_restore manual.