Transactions - What's it all about? 
 
 
- Far more than just locking
- The A.C.I.D. test
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- Atomicity - Consistency - Isolation - Durability  
 
- True transactions give true safety
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- even from power failures and system crashes!
- Incomplete transactions are automatically rolled-back by the database server when it's restarted.
 
- Also removes burden of undoing incomplete changes
- Hard to implement (for the vendor)
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- and can have significant performance cost
 
- A very large topic worthy of an entire tutorial