Add RFC: RawKV Stale Read #80
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Signed-off-by: Andy Lok <andylokandy@hotmail.com>
Signed-off-by: Andy Lok <andylokandy@hotmail.com>
Signed-off-by: Andy Lok <andylokandy@hotmail.com>
Signed-off-by: Andy Lok <andylokandy@hotmail.com>
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What's the guarantees stale read provides? It seems there is no guarantee at all, client may read a key's value and then read no keys and then read the keys again even if there is no changes to the key. |
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@BusyJay This is exactly what eventually consistency means. To address these problems, the client can select the store with a satisfied RPO so that the freshness will not regress. |
BusyJay
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Jun 4, 2022
| message RaftRequestHeader { | ||
| ... | ||
| bool replica_read = 8; | ||
| + bool direct_read = 9; |
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We already have the STALE_READ write batch flags, the new field may not be necessary.
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Signed-off-by: Andy Lok andylokandy@hotmail.com
Summary
Allow eventually consistency on RawKV.
Motivation
Eventually consistency is acceptable in some scenarios when using RawKV. In this case, RawKV is allowed to break linear consistency and therefore improve the cluster-wise throughput.
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