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关于使用索引的一些经验
hash索引只能显示应用于heap引擎表。
索引设计原则:
1.一个索引里包含的列数,最好不要超过5个。
2.一个表的索引数,也不要太多,一般也不要超过5个。
3.联合索引中,把过滤性高(基数大)的列放在前面。
MySQL索引限制:
1.不支持混合顺序。
2.不支持位图索引。
3.不支持函数索引。
4.不支持表达式索引。
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原文地址:https://www.cnblogs.com/l10n/p/8901018.html
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