Em 24/10/2023 17:31, Tom Lane escreveu: > Carlos Alves <carlos.al...@tecnisys.com.br> writes: > >> I need some help to understand why a transaction wiht a row delete >> aquire a AccessExclusiveLock and a row update a ExclusiveLock. > > UPDATE can use the weaker lock type if it's not modifying any > column that is part of a unique index. This is to allow concurrency > with foreign-key checks that might wish to grab a read-only (shared) > lock on such a tuple. > > A DELETE, or an UPDATE that is modifying key columns, has to > conflict with foreign-key checks. > > regards, tom lane
Tom, thank you very much for your straight to the point answer! regards Carlos Alves
