Hello, I find a bug in building historic snapshot and the steps to reproduce are as follows:
Prepare: (pub)create table t1 (id int primary key); (pub)insert into t1 values (1); (pub)create publication pub for table t1; (sub)create table t1 (id int primary key); Reproduce: (pub)begin; insert into t1 values (2); (txn1 in session1) (sub)create subscription sub connection 'hostaddr=127.0.0.1 port=5432 user=xxx dbname=postgres' publication pub; (pub will switch to BUILDING_SNAPSHOT state soon) (pub)begin; insert into t1 values (3); (txn2 in session2) (pub)create table t2 (id int primary key); (session3) (pub)commit; (commit txn1, and pub will switch to FULL_SNAPSHOT state soon) (pub)begin; insert into t2 values (1); (txn3 in session3) (pub)commit; (commit txn2, and pub will switch to CONSISTENT state soon) (pub)commit; (commit txn3, and replay txn3 will failed because its snapshot cannot see t2) Reasons: We currently don't track the transaction that begin after BUILDING_SNAPSHOT and commit before FULL_SNAPSHOT when building historic snapshot in logical decoding. This can cause a transaction which begin after FULL_SNAPSHOT to take an incorrect historic snapshot because transactions committed in BUILDING_SNAPSHOT state will not be processed by SnapBuildCommitTxn(). To fix it, we can track the transaction that begin after BUILDING_SNAPSHOT and commit before FULL_SNAPSHOT forcely by using SnapBuildCommitTxn(). -- Regards, ChangAo Chen
0001-Track-transactions-committed-in-BUILDING_SNAPSHOT.patch
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