Are all unlogged tables in any case truncated after a server-crash?

Hi everyone,

every few weeks I use Postgres ability, to import huge data sets very
fast by means of "unlogged tables". The bulk load (consisting of plenty
"copy"- & DML-Stmts) and the spatial index creation afterwards, takes
about 5 hours on a proper server  (pg12.7 & PostGIS-Extension). After
that all unlogged tables remain completely unchanged (no
DML-/DDL-Statements). Hence all of my huge unlogged, "static" tables get
never "unclean" and should not be truncated after a server crash.

BTW, if I set all unlogged tables to logged after bulk load, it takes
additional 1.5 hours, mainly because of re-indexing, I suppose. I assume
that a restart of the database after a server crash takes another 1.5
hours (reading from WAL) until the database is up and running.

Therefore I am seeking a strategy, to not tagging those tables as
"unclean" and not truncating all unlogged tables on server restart.

Cheers and regards.