Laurenz Albe <laurenz.albe@xxxxxxxxxxx> writes: > On Thu, 2023-03-09 at 08:37 +0000, James Pang (chaolpan) wrote: >> Both follow "C" collate behavior ,right? > Right. There is another difference: "C" is a built-in collation, while "C.latin1" must have been something that initdb made because "locale -a" claimed it exists on your platform. Postgres has some optimizations built in for "C" (and its equivalent "POSIX") that will not apply for "C.latin1". So while they should be behaviorally the same, "C.latin1" is likely to be slower. regards, tom lane