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什么是index的leading column（索引的前导列）？
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作者: warehouse(http://warehouse.itpub.net)
发表于: 2008.04.22 18:30
分类: 性能优化
出处: http://warehouse.itpub.net/post/777/460380
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发表于: 2008.04.22 18:30
分类: 性能优化
出处: http://warehouse.itpub.net/post/777/460380
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看到经常有人问此问题！doc的原话，看到了随手记录下！
A leading portion of an index is a set of one or more columns that were specified first and consecutively in the list of columns in the CREATE INDEX statement that created the index. Consider this CREATE INDEX statement:
CREATE INDEX comp_ind ON table1(x, y, z);
x,xy, andxyzcombinations of columns are leading portions of the indexyz,y, andzcombinations of columns are not leading portions of the index
re: 什么是index的leading column（索引的前导列）？ 
