Page 282 - CISSO_Prep_ Guide

• Isolation = results are not visible
until transaction is complete.
• Durability = completed transaction
is permanent.
▪ Mnemonic:
• All: all or none.
• Changes: consistency maintained
during change
[are]
• Invisible: in-progress changes are
hidden
[until]
• Done: when you say it’s done, it stays
done even in the event of a crash.
• OLTP = online transaction processing:
▪ Security concerns are concurrency and
atomicity
• Concurrency = two users cannot
simultaneously change the same
data
• Atomicity (defined above as well)
= if one step fails, all steps should
not complete.
• Often uses journaling (back up in
real-time) and transaction logs to
do this.
▪ OLTP systems use 2 phase commit
process:
• 1) write across all databases.
• 2) commit to all databases.
• Ensures atomicity.