• Do not index on columns that are frequently updated and poorly differentiated, otherwise, the database performance will deteriorate.
• When using the LIKE keyword, do not use a percent sign (%) before searching pattern strings. Otherwise, the index may fail and affect query performance.
• Do not index on columns with null values. In general, indexes are not built on columns with null values.
• When using the OR keyword, make sure that the left and right fields of the OR operator are indexed. If one field is indexed and the other is not, the indexed field also becomes invalid.
• Do not use! =operator. The uncertainty of the scope reduces the use efficiency of the index, and the database engine automatically changes to a full table scan.
• Do not perform operations on indexed fields. Otherwise, the index may fail and affect query performance.
• When using a compound index, follow the leftmost prefix principle and ensure that the first field of the index is used in the query, otherwise, the index becomes invalid. To maximize the efficiency of the index, try to keep the order of the fields in the query the same as the order of the index.
To sum up, by following the precautions and recommendations, you can optimize the use of MySQL indexes and improve the query performance and response speed of the database. In practical applications, it is extremely important to optimize the index according to the specific service requirements and data characteristics. Meanwhile, regularly monitoring and optimizing the use of indexes can further improve the performance and efficiency of the database.