It looks like it got past creating the exclude constraint based on the
ordering of commands in the dump file. However creating a more normal
spgist index is taking a very long time with a lot of disk wait time.
CPU usage seems pretty low for the amount of time it has been working
on building that index, but maybe that is normal for building indexes.
I used the almost the default postgresql.conf on my workstation. I bumped
up the limits in a few places on the server that could have allowed a lot
more memory to be used especially if the index creation was parallelized.
While the load is running I'll see if I can tell if there is a memory leak
with this index build. Once it finishes, I can dump a specific table
and test building the exclude spgist index with some different settings
to see if I can reproduce the out of memory error with a lot less data
then is in the whole database.