Row compression requires the creation of a dictionary which stores a mapping between repetitive patterns or entries and numeric keys.
行压缩要求创建一个词典，它存储重复的模式或条目与数字键之间的映射。
2
NULL values are stored with only three bytes, if value compression is active. You can expect space savings especially for numeric values.
如果激活值压缩，则null值的存储只需3个字节。
3
We use period extension or symmetry extension in image processing. Our arithmetic has perfect properties that validated by numeric experiments in image compression.