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Database concurrency control with precision:
- rthogonal key-value locking
Goetz Graefe
Locks vs latches
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Database concurrency control with precision: orthogonal key-value - - PowerPoint PPT Presentation
Database concurrency control with precision: orthogonal key-value - - PowerPoint PPT Presentation
Database concurrency control with precision: orthogonal key-value locking Goetz Graefe Locks vs latches 2 Transaction isolation levels Snapshot isolation great for read-only transactions on multi-version storage 0. No locks no
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Transaction isolation levels
Snapshot isolation – great for read-only transactions on multi-version storage 0. No locks – no concurrency control 1. Dirty read – only write locks, no locks for reads 2. Cursor stability – short read locks 3. Repeatable read – read locks on presence but not on absence 4. Serializable – “repeatable count” – locks on predicates or on gaps Simple and reliable transaction logic requires ___ .
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Example table + secondary index
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Example table + secondary index
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Orthogonal key-value locking
Summary of possible lock scopes:
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Phantom protection
Select count (*) where FirstName = ‘Harry’
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Gerhard, Gottfried, Hank
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Equality queries
Select count (*) where FirstName = ‘Jerry’
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James Jim
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Range queries
...where FirstName between ‘Jerry’ and ‘Mary’
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Irv Mohan
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Non-key updates
...where row# = 3 Non-key fields (“include” syntax), deletion (to ghost), insertion (from ghost)
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Phantom protection with a ghost
Select count (*) where FirstName = ‘Harry’
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