日期:2014-05-16  浏览次数:20515 次

数据库事务转载基础二:oracle事务隔离级别

Oracle 支持的 2 种事务隔离级别 Read committed Serializable

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来自 oracle 官方网站的 Read committed Serializable 的解释

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Isolation Level

Description

Read committed

This is the default transaction isolation level. Each query executed by a transaction sees only data that was committed before the query (not the transaction) began. An Oracle query never reads dirty (uncommitted) data.

Because Oracle does not prevent other transactions from modifying the data read by a query, that data can be changed by other transactions between two executions of the query. Thus, a transaction that runs a given query twice can experience both nonrepeatable read and phantoms.

Serializable

Serializable transactions see only those changes that were committed at the time the transaction began, plus those changes made by the transaction itself through INSERT , UPDATE , and DELETE statements. Serializable transactions do not experience nonrepeatable reads or phantoms.

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