Hi, When pg_recvlogical loses connection, it reconnects and restarts replication unless --no-loop option is used. I noticed that in this scenario, data that has already been flushed can be re-sent after restarting replication. This happens because the replication start position used when restarting replication is taken from the write position in the last status update message, which may be older than the actual position of the last flushed data. As a result, some flushed data could exist newer than the replication start position and be re-sent. Is this a bug?
To fix this issue, I'd like to propose the attached patch that fixes this by ensuring all written data is flushed to disk before restarting replication and by using the last flushed position as the replication start point. This prevents already flushed data from being re-sent. Additionally, when the --no-loop option is used, I found that pg_recvlogical could previously exit without flushing written data, risking data loss. The attached patch fixes this issue by also ensuring that all data is flushed to disk before exiting with --no-loop. Thought? Regards, -- Fujii Masao
v1-0001-pg_recvlogical-Prevent-flushed-data-from-being-re.patch
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