Ivan Rakov created IGNITE-8529:
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Summary: Implement testing framework for checking delta records
consistency
Key: IGNITE-8529
URL: https://issues.apache.org/jira/browse/IGNITE-8529
Project: Ignite
Issue Type: New Feature
Components: persistence
Reporter: Ivan Rakov
We use sharp checkpointing of page memory in persistent mode. That implies that
we write two types of record to write-ahead log: logical (e.g. data records)
and phyisical (page snapshots + binary delta records). Physical records are
applied only when node crashes/stops during ongoing checkpoint. We have the
following invariant: checkpoint #(n-1) + all physical records = checkpoint #n.
If correctness of physical records is broken, Ignite node may recover with
incorrect page memory state, which in turn can bring unexpected delayed errors.
However, consistency of physical records is poorly tested: only small part of
our autotests perform node restarts, and even less part of them performs node
stop when ongoing checkpoint is running.
We should implement abstract test that:
1. Enforces checkpoint, freezes memory state at the moment of checkpoint.
2. Performs necessary test load.
3. Enforces checkpoint again, replays WAL and checks that page store at the
moment of previous checkpoint with all applied physical records exactly equals
to current checkpoint state.
Except for checking correctness, test framework should do the following:
1. Gather statistics (like histogram) for types of wriiten physical records.
That will help us to know what types of physical records are covered by test.
2. Visualize expected and actual page state (with all applied physical records)
if incorrect page state is detected.
Regarding implementation, I suppose we can use checkpoint listener mechanism to
freeze page memory state at the moment of checkpoint.
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