Re: Question about tuple´s lock

Em 24/10/2023 17:31, Tom Lane escreveu:

Carlos Alves <carlos.alves@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