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Today, I would like to share with you the relevant knowledge of what the specification of the mysql index is. The content is detailed and the logic is clear. I believe most people still know too much about this, so share this article for your reference. I hope you can get something after reading this article. Let's take a look.

1. It is recommended that the index of a single table be controlled within 5.

2. The number of combined index fields is not recommended to exceed 5.

3. Join forbids more than three tables.

For fields that require join, the data type must be absolutely consistent.

4. It is strictly forbidden to be left fuzzy or full fuzzy, if you need to solve it with a search engine.

5. If there is an orderby scenario, please pay attention to the ordering of the index.

Example

1) there is at most one matching row (primary key or unique index) in a single consts table, and the data can be read in the optimization phase. 2) ref refers to the use of a normal normal index. 3) range searches the range of the index. Counterexample: the result of explain table, type=index, index physical file full scan, the speed is very slow, this index level is lower than range, and is negligible compared with full table scan. These are all the contents of this article entitled "what is the specification of mysql index?" Thank you for reading! I believe you will gain a lot after reading this article. The editor will update different knowledge for you every day. If you want to learn more knowledge, please pay attention to the industry information channel.

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