如果编目中没有列数据值分布信息，DB 2就会假设值是均匀分布的，这可能导致优化器选择非最优的访问路径。
Without column data-value distribution information in the catalog, DB2 will assume an even distribution of values, which may lead the optimizer to a sub-optimal access path.
在地震层析研究中，常常涉及地震波在非均匀介质中的传播路径问题，故快速射线追踪是不可缺少的工具。
The problem of the seismic wave travel path in the nonhomogeneous medium is often mentioned in seismic sequence analysis by means of rapid ray tracing.
当声波在非均匀温度场中传播时会因声波的折射而导致声波路径弯曲。
When a sound wave passes through non-uniform temperature fields, it will be refracted and its travel path will be bended.
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