postgresql - Locking a newly created, uncommitted row in two concurrent READ COMMITTED database transactions -


if have 2 read committed postgresql database transactions both create new row same primary key , lock row, possible acquire both locks @ same time?

my instinct yes since these new rows both exist in individual transactions' scopes, curious if new rows , locking handled differently between transactions.

no.
primary keys implemented unique (currently only) b-tree index. happens when trying write index, per documentation:

if conflicting row has been inserted as-yet-uncommitted transaction, would-be inserter must wait see if transaction commits. if rolls there no conflict. if commits without deleting conflicting row again, there uniqueness violation. (in practice wait other transaction end , redo visibility check in toto.)

bold emphasis mine.
can try 2 open transactions (two different sessions) in parallel.


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