As we all know, there are usually 4 kinds isolation levels in transaction database: Read Uncommitted
, Read Committed
, Repeatable Read
and Serializable
.
Repeatable Read
and Serializable
can avoid Nonrepeatable Read
.
Such as, Transaction_1 has two selects, and Transaction_2 has one update, the update executes between the two selects, why we must avoid this?
Who can find a application that must avoids the Nonrepeatable Read
?
Are there some applications about shopping and transfer?
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egraldlo
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Depends on your application if you have to avoid it... – Thilo May 18 '15 at 06:19
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thanks! yes, but what kind of application, it's easy to find a application which must avoid "dirty read", but how about "nonrepeatable read"? – egraldlo May 18 '15 at 06:22
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1I saw this gif of a gag about guy going in to the lavatories, he checks the sign and heads for the one for mens. Once he enters he quickly realizes it was actually full of women and comes out and checks the signs again (they were flipped over while he was in by some other guys) and goes to the other one which is for mens. – Janne Matikainen May 18 '15 at 06:23
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are there some applications about shopping or transfer? – egraldlo May 18 '15 at 06:28