Database migration is a comprehensive activity as the volumeof changes required might be huge.
数据库迁移是一种复杂的活动，因为可能需要做大量修改。
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Threshold, though a new feature, bases its migrationof a volume on the threshold (default 95%). Following are a few quick facts on threshold migration.
阈值是一项新特性，它使一个卷的移植以阈值(默认为95%)为基础。
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And Darcy flow production equation with gas-bearing volume may reflect the characteristics of methane migration in coal measure strata more really.