Michael reported a BF failure [1] related to one of the logical streaming test case and I've analyzed the issue. As responded on pgsql-committers [2], the issue here is that the streaming transactions can be interleaved and because we are maintaining whether xact_wrote_changes at the LogicalDecodingContext level, one of later transaction can overwrite the flag for previously streaming transaction. I think it is logical to have this flag at each transaction level (aka in ReorderBufferTxn), however till now it was fine because the changes of each transaction are decoded at one-shot which will be no longer true. We can keep a output_plugin_private data pointer in ReorderBufferTxn which will be used by test_decoding module to keep this and any other such flags in future. We need to set this flag at begin_cb and stream_start_cb APIs and then reset/remove it at stream_commit_cb, stream_abort_cb and stream_stop_cb APIs.
Additionally, we can extend the existing test case concurrent_stream.spec to cover this scenario by adding a step to have an empty transaction before the commit of transaction which we are going to stream changes for (before s1_commit). Thoughts? [1] - https://www.postgresql.org/message-id/20201109014118.GD1695%40paquier.xyz [2] - https://www.postgresql.org/message-id/CAA4eK1JMCm9HURVmOapo%2Bv2u2EEABOuzgp7XJ32C072ygcKktQ%40mail.gmail.com -- With Regards, Amit Kapila.
