release-19.1: changefeedccl: fix job progress regressing #37091
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nvanbenschoten
approved these changes
Apr 24, 2019
When the ChangeFrontier processor for a changefeed is started up, it creates a spanFrontier to track the overall progression for the feed. Each watched span is set to the empty timestamp so we can tell the difference between a rangefeed being behind and one still initializing. However, rangefeed will happily return resolved timestamps less than the one it was started with. If we feed this into the spanFrontier, it can report a timestamp behind the one everything started up at. In the case of a new changefeed, this is fine (though perhaps odd). In the case of a changefeed being restarted from the job's high-water, this means we can overwrite the high-water progress with the lower value, regressing it. At the least, this is very surprising UX, but it's easy to argue that it's a correctness issue. Touches cockroachdb#36879 Release note (bug fix): Fixed a bug where `CHANGEFEED` job progress would regress when the job was restarted.
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Backport 1/2 commits from #37009.
/cc @cockroachdb/release
Targeting 19.1.1
When the ChangeFrontier processor for a changefeed is started up, it
creates a spanFrontier to track the overall progression for the feed.
Each watched span is set to the empty timestamp so we can tell the
difference between a rangefeed being behind and one still initializing.
However, rangefeed will happily return resolved timestamps less than the
one it was started with. If we feed this into the spanFrontier, it can
report a timestamp behind the one everything started up at. In the case
of a new changefeed, this is fine (though perhaps odd). In the case of a
changefeed being restarted from the job's high-water, this means we can
overwrite the high-water progress with the lower value, regressing it.
At the least, this is very surprising UX, but it's easy to argue that
it's a correctness issue.
Touches #36879
Release note (bug fix): Fixed a bug where
CHANGEFEEDjob progresswould regress when the job was restarted.