(1) Postgres default settings, 5GB CSV (5100000 rows), no indexes on table:

Copy Type			Duration (s)	Load factor
===============================================
Normal Copy			132.838			-

Parallel Copy
(#workers)
1					97.537			1.36
2					61.700			2.15
3					52.788			2.52
4					46.607			2.85
5					45.524			2.92
6					43.799			3.03
7					42.970			3.09
8					42.974			3.09
9					43.698			3.04
10					43.362			3.06


(2) Postgres default settings, 5GB CSV (5100000 rows), 4 indexes on table:

Copy Type			Duration (s)	Load factor
===============================================
Normal Copy			221.111			-

Parallel Copy
(#workers)
1					331.609			0.66
2					99.085			2.23
3					89.751			2.46
4					81.137			2.73
5					79.138			2.79
6					77.155			2.87
7					75.813			2.92
8					74.961			2.95
9					77.803			2.84
10					75.399			2.93


(3) Postgres increased resources, 5GB CSV (5100000 rows), no indexes on table:

shared_buffers = 20% of RAM (total RAM = 376GB) = 76GB
work_mem = 10% of RAM = 38GB
maintenance_work_mem = 10% of RAM = 38GB
max_worker_processes = 16
max_parallel_workers = 16 
checkpoint_timeout = 30min
max_wal_size=2GB


Copy Type			Duration (s)	Load factor
===============================================
Normal Copy			78.138			-

Parallel Copy
(#workers)
1					95.203			0.82
2					62.596			1.24
3					52.318			1.49
4					48.246			1.62
5					42.832			1.82
6					42.921			1.82
7					43.146			1.81
8					41.557			1.88
9					43.489			1.80
10					43.362			1.80


(4) Postgres increased resources, 5GB CSV (5100000 rows), 4 indexes on table:

Copy Type			Duration (s)	Load factor
===============================================
Normal Copy			151.364			-

Parallel Copy
(#workers)
1					120.058			1.26
2					87.465			1.73
3					76.871			1.97
4					69.805			2.17
5					64.100			2.36
6					60.667			2.49
7					59.202			2.56
8					57.417			2.67
9					61.143			2.48
10					57.500			2.63