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Mysql索引优化 #3

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merlinpanda opened this issue May 10, 2022 · 1 comment
Open

Mysql索引优化 #3

merlinpanda opened this issue May 10, 2022 · 1 comment

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@merlinpanda
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索引分类

单值索引

CREATE INDEX index_name ON Table(field)

复合索引

CREATE INDEX idx_ABC ON TableName(a,b,c)

唯一索引

CREATE UNIQUE INDEX idx_d ON TableName(d)

索引结构

  • B树
  • 哈希 Hash
  • 全文索引
  • R树索引
@merlinpanda
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避免索引失效

  1. 全值索引：比如索引中有a、b、c三个字段，查询时WHERE a = 1 AND b = 2 AND c=3，即索引中的字段全用到

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@merlinpanda