Hi, When developing another feature, I find an existing bug which was reported from Dilip[1].
Currently, it's possible that we only send a streaming block without sending a end of stream message(stream abort) when decoding and streaming a transaction that was aborted due to crash because we might not WAL log a XLOG_XACT_ABORT for such a crashed transaction. This will cause the subscriber(with streaming=on) create a stream file but won't delete it until the apply worker restart. BUG repro(borrowed from Dilip): --- 1. start 2 servers(config: logical_decoding_work_mem=64kB) ./pg_ctl -D data/ -c -l pub_logs start ./pg_ctl -D data1/ -c -l sub_logs start 2. Publisher: create table t(a int PRIMARY KEY ,b text); create publication test_pub for table t with(PUBLISH='insert,delete,update,truncate'); alter table t replica identity FULL ; 3. Subscription Server: create table t(a int,b text); create subscription test_sub CONNECTION 'host=localhost port=10000 dbname=postgres' PUBLICATION test_pub WITH ( slot_name = test_slot_sub1,streaming=on); 4. Publication Server: begin ; insert into t values (generate_series(1,50000), 'zzzzzzzzz'); -- (while executing this restart publisher in 2-3 secs) Restart the publication server, while the transaction is still in an uncommitted state. ./pg_ctl -D data/ -c -l pub_logs restart -mi --- After restarting the publisher, we can see the subscriber receive a streaming block and create a stream file(/base/pgsql_tmp/xxx.fileset). To fix it, One idea is to send a stream abort message when we are cleaning up crashed transaction on publisher(e.g. in ReorderBufferAbortOld()). And here is a tiny patch which changes the same. I have confirmed that the bug is fixed and all regression tests pass. I didn't add a testcase because we need to make sure the crash happens before all the WAL logged transactions data are decoded which doesn't seem easy to write a stable test for this. Thoughts ? [1] https://www.postgresql.org/message-id/CAFiTN-sTYk%3Dh75Jn1a7ee%2B5hOcdQFjKGDvF_0NWQQXmoBv4A%2BA%40mail.gmail.com Best regards, Hou zj
0001-fix-stream-changes-for-crashed-transaction.patch
Description: 0001-fix-stream-changes-for-crashed-transaction.patch
