Principles of Transaction Management. Outline. Transaction concepts & protocols Performance impact of concurrency control Performance tuning. Application Programmer (e.g., business analyst, Data architect). Application. Sophisticated Application Programmer (e.g., SAP admin).
SophisticatedApplicationProgrammer(e.g., SAP admin)
Hardware[Processor(s), Disk(s), Memory]
t1 t2 t3 t4 t5
T1 transfer $100 from A to B, and T2 increments both and B by 6%
(A and B have $200 initially)
Unrepeatable Read (UR)
T1 to set both A and B to $1000, T2 to set both A and B to $2000
X == Y (orignal X + originalY)
For serializable T1T2,
X == X + Y
Y == 2Y + originalX?
Cannot serialize T1 and T2
Phase 1: Growing
Phase 2: Shrinking
What is the best item size?
Processing a mix of transactions?
Depends on the type of transactions
Multiple granularity locking scheme, changing the size of the data item dynamically
# of Active Transactions
To improve performance
Serial schedule is correct
Serializable schedule is equivalent to some serial schedule
Concurrency control enforces serializability