Hi,
we're discussing a system design and it boils down to a question
regarding commit timestamps (in the sense of [1],
track_commit_timestamp='on'):
We have a insert-only (append-only) table. Do commit timestamps on
this table constitute the same order in which records become visible
on a secondary (streaming replication)? Is there any reason why this
might not be the case?
To put this differently: If a client reads from a secondary and reads
the "latest" record by commit timestamp (commit time T). Is it safe to
assume that there won't ever be another record with a lower commit
timestamp < T, that only shows up on the secondary after that read?
I'm aware of concerns regarding physical time, time adjustments and so
on, so the question here assumes those things never happen.
Thank you!
Best regards,
Andreas
[1] https://wiki.postgresql.org/wiki/What%27s_new_in_PostgreSQL_9.5#Commit_timestamp_tracking