Holger Jakobs <holger@jakobs.com> writes:
> Am 07.12.23 um 19:11 schrieb Rajesh Kumar:
>> Will pg_dump cause blocking queries? If so how to take dump without
>> blocking?
> Readers don't block writers, writers don't block readers in PostgreSQL.
> pg_dump is a reader.
To enlarge on that a bit: pg_dump takes AccessShareLock on every
table it intends to dump. This does not conflict with ordinary
DML updates. It *will* conflict with anything that wants
AccessExclusiveLock, which typically is schema-altering DDL.
See
https://www.postgresql.org/docs/current/explicit-locking.html#LOCKING-TABLES
So the answer to your question is "don't try to alter the
database schema while pg_dump is running". You can alter
database content freely, though.
regards, tom lane
