Multi-version Concurrency Control (cont)
When a writer Ti attempts to change a data item
- find newest version V satisfying WTS(V) < TS(Ti)
- if no later versions exist, create new version of data item
- if there are later versions, then abort Ti
Some MVCC versions also maintain RTS (TS of last reader)
- don't allow Ti to write D if RTS(D) > TS(Ti)
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