MySQL Partial index

Partial index

Char/varchar2 too long, all indexed, inefficient, waste storage space

Select AVG (length (username)) from

Index statistics:

• Show index from table
• SELECT * FROM I_s.statistics
• Mysql.innodb_index_stats

MySQL5.7 Index Utilization:

Select index_name,rows_selected,rows_updated,rows_deleted from Schema_index_statistics where table_schema= ' Scott ' and table_name= ' EMP ';

View Redundant indexes: schema_redundant_indexes

An implicit conversion of an index:

SELECT * from t1 where user=123; Do not use the index of the user column to first convert the user to Assic code

MySQL Partial index