如果有一个包含大量读取操作的工作负载，那么您可能想将隔离级别设置为未提交读取(UR)，从而不需要在每个语句中设置隔离级别。
If you have a read-heavy workload, you might want to set isolation to uncommitted read (UR) at the connection level so that you don't have to specify it in each statement.
在读事务中，没有变更需要提交，但是事务会防止对正在被读取的数据的修改，直到所有的读操作全部结束。
In a read transaction, there are no changes to commit, but the transaction prevents the data being read from changing until all of the reads are complete.
如果另一个进程要读取数据库，则不会看到此键，因为它是没有提交。
If another process were to be reading the database, it would not see this key, because it is not committed.
现在，读取事务可以访问当前提交的、连贯的行映像(写入事务以不兼容方式锁定)，而不会受到阻塞。
Now, a read transaction can access the currently committed and consistent image of rows that are incompatibly locked by write transactions without being blocked.
在5分钟的提交事务时间之后，次要节点将从暂存目录LOG_STAGING_DIR读取事务，然后应用它们。
After 5 minutes of commit transaction time, the secondary node will read the transactions from the staging directory LOG_STAGING_DIR and apply them.
不过，让其事务看到未提交的数据可以带来意料之外的副作用，如更新冲突和读取不一致等。
Letting uncommitted data be seen by other transactions, however, can result in unexpected side effects, such as clashing updates and inconsistent reads.
向LoginAction添加一些代码，以便读取由用户提交的凭证并针对数据库检查凭证(参见清单33)。
Add some code to the LoginAction that reads the credentials submitted by the user and checks them against the database (Listing 33).
应用程序提交一个SQL或XQuery语句以读取XML文档。
The application submits an SQL or XQuery statement to read an XML document.
例如，如果一个成员正在更新一行数据，那么另一个成员就不能以未提交读(uncommitted read)以外的任何隔离级别读取这一行。
For example, if one member is updating a row, it would not be proper for another member to read the row with any other isolation level than uncommitted read.
例如，可以每分钟调用一次收集器来读取主机的cpu利用率，或通过JXM接口从事务管理器读取提交事务的总数。
For example, a collector might be invoked every minute to read a host's CPU utilization or read the total number of committed transactions from a transaction manager through a JMX interface.
相反，它们会读取这一行的当前已经提交的版本。
Instead they will read the currently committed version of the row.
该数字有用的地方是它增加的速率，因此定期收集它的绝对值并跟踪每次读取数据之间的增量可以反映事务提交的速率。
The number's useful aspect is the rate at which it increases, so collecting the absolute number on a regular period and tracing the delta between readings reflects the rate of transaction commits.
事务再次读取某数据时发现它自最后一次读操作之后由于另一个事务修改并提交了该数据而发生了更改，则会发生不可重读。
An unrepeatable read can occur when the transaction reads some data again and finds that it changed since the last read due to another transaction that modified this data and committed.
Readcommitted（读已提交） ——事务可以读取由另一事务提交的数据。
Read committed -- The transaction can read data committed by other transactions.
比如，读取只读的查找表不需要可重复读级别，未提交读级别就足够了。
For example, reading from a read - only look up table doesn t require repeatable read, and uncommitted read is sufficient.
比如，读取只读的查找表不需要可重复读级别，未提交读级别就足够了。
For example, reading from a read - only look up table doesn t require repeatable read, and uncommitted read is sufficient.
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