Roman Kondakov created IGNITE-9590:
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Summary: MVCC: Cleanup old rows in the vacuum thread.
Key: IGNITE-9590
URL: https://issues.apache.org/jira/browse/IGNITE-9590
Project: Ignite
Issue Type: Improvement
Components: mvcc
Reporter: Roman Kondakov
When updating writer thread should iterate over the set of the last versions in
order to find an appropriate version for its MVCC snapshot. During this
iteration it collects invisible to anybody versions (their xid_max version is
less than cleanup). When all outdated versions found, writer thread cleanups
these rows - removes it from indexes and from pagestore.
It would be more efficient if writer thread does not cleanup old rows by
itself, but rather delegate it to vacuum workers: instead of cleaning just put
it to cleanup queue.
in case of significant backpressure during active updates, when cleanup workers
can't keep up with removing outdated rows and cleanup queue is too big, writer
threads can cleanup this rows by itself to prevent memory and performance
problems.
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