表数据倾斜指的是特定的一些数据库分区上的某个表内的记录数与这个表所跨的所有数据库分区的平均记录数之间的差额。

Table data skew refers to a difference between the number of records in a table on particular database partitions and the average number of records across all database partitions for this table.

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尤其是有一两千万行数据的时候，每次修改模式、往数据库中添加索引都会数小时完全锁定数据库。

In particular, making schema changes or adding indexes to a database with more than 10-20 million rows completely locks the database for hours at a time.

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默认情况下，如果条目数超过1000或距上次执行已有五分钟，数据库会话执行写入本地历史的操作。

By default, the database session commits local history if the number of entries exceeds 1000 or if it has been five minutes since the last database commit.

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It's defined in CS50's library; its sole purpose in life is to ask the user for a floating point value and return it.

它被定义在CS50的函数库中，它的唯一目的是,向用户询问一个浮点数的值，然后返回它。

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