CONCURRENCY CONTROL

azzaiqmal
Mind Map by , created over 5 years ago

Mind Map on CONCURRENCY CONTROL, created by azzaiqmal on 04/09/2014.

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azzaiqmal
Created by azzaiqmal over 5 years ago
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CONCURRENCY CONTROL
1 Problem Definition
1.1 Objective
1.1.1 Maximize transaction throughput(work perform) while preventing interference among multiple users
1.1.2 Throughput: number of transactions processed per unit time eg >1million transaction per second
1.2 Constraint
1.2.1 No interference: result same as serial/sequential effect
1.2.2 Interference occurs on commonly manipulated data known as hot spots
2 Concurrency Control Problem
2.1 Lost Update Problem e.g:slide no.11&12
2.1.1 Preventing Lost Update Problem Using 2PL e.g:slide no.28
2.2 Uncommitted Dependency Problem e.g:slide no.13&14
2.2.1 Preventing Uncommitted Using 2PL e.g:slide no.29
3 Concurrency Control Tools
3.1 Locking
3.1.1 Obtain lock before accessing an item
3.1.2 Wait if a conflicting lock is held
3.1.2.1 Shared lock (S lock): conflicts with exclusive locks
3.1.2.2 Exclusive lock (X lock): conflicts with all other kinds of locks
3.1.3 Locking Conflict e.g:slide no.22
3.1.4 Locking Granularity e.g:slide no 23
3.2 Deadlock
3.2.1 Deadlock(Mutual Waiting) e.g:slide no.24
3.2.2 Deadlock Resolution
3.2.2.1 Detection
3.2.2.1.1 Overhead is reasonable for deadlocks among 2 or 3 transactions
3.2.2.2 Timeout
3.2.2.2.1 Waiting limit
3.2.2.2.2 Can abort transactions that are not deadlocked
3.2.2.2.3 Timeout interval is difficult to determine

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