On Tue, Mar 7, 2023 at 7:17 PM Önder Kalacı <onderkal...@gmail.com> wrote: > >> >> > > Let me give an example to demonstrate why I thought something is fishy >> > > here: >> > > >> > > Imagine rel has a (non-default) REPLICA IDENTITY with Oid=1111. >> > > Imagine the same rel has a PRIMARY KEY with Oid=2222. >> > > > > > Hmm, alright, this is syntactically possible, but not sure if any user > would do this. Still thanks for catching this. > > And, you are right, if a user has created such a schema, > IdxIsRelationIdentityOrPK() > would return the wrong result and we'd use sequential scan instead of index > scan. > This would be a regression. I think we should change the function. > > > Here is the example: > DROP TABLE tab1; > CREATE TABLE tab1 (a int NOT NULL); > CREATE UNIQUE INDEX replica_unique ON tab1(a); > ALTER TABLE tab1 REPLICA IDENTITY USING INDEX replica_unique; > ALTER TABLE tab1 ADD CONSTRAINT pkey PRIMARY KEY (a); >
You have not given complete steps to reproduce the problem where instead of the index scan, a sequential scan would be picked. I have tried to reproduce by extending your steps but didn't see the problem. Let me know if I am missing something. Publisher ---------------- postgres=# CREATE TABLE tab1 (a int NOT NULL); CREATE TABLE postgres=# Alter Table tab1 replica identity full; ALTER TABLE postgres=# create publication pub2 for table tab1; CREATE PUBLICATION postgres=# insert into tab1 values(1); INSERT 0 1 postgres=# update tab1 set a=2; Subscriber ----------------- postgres=# CREATE TABLE tab1 (a int NOT NULL); CREATE TABLE postgres=# CREATE UNIQUE INDEX replica_unique ON tab1(a); CREATE INDEX postgres=# ALTER TABLE tab1 REPLICA IDENTITY USING INDEX replica_unique; ALTER TABLE postgres=# ALTER TABLE tab1 ADD CONSTRAINT pkey PRIMARY KEY (a); ALTER TABLE postgres=# create subscription sub2 connection 'dbname=postgres' publication pub2; NOTICE: created replication slot "sub2" on publisher CREATE SUBSCRIPTION postgres=# select * from tab1; a --- 2 (1 row) I have debugged the above example and it uses an index scan during apply without your latest change which is what I expected. AFAICS, the use of IdxIsRelationIdentityOrPK() is to decide whether we will do tuples_equal() or not during the index scan and I see it gives the correct results with the example you provided. -- With Regards, Amit Kapila.
