Summary of related content about mysql index length

MySQL Optimization - Index specific code analysis: Indexes are implemented in storage engines, so the indexes of each storage engine are not necessarily exactly the same, and each storage engine does not necessarily support all index types. Define the maximum number of indexes and maximum index length for each table according to the storage engine. All storage engines support at least 16 indexes per table, with a total index length of at least 256 bytes. Most storage engines have higher limits. There are two storage types of indexes in MYSQL: BTREE and HASH, which are specifically related to the storage engine of the table; MYISAM and InnoDB storage engines only support BTREE indexes; MEMORY and HEAP storage engines can support HASH and BTREE indexes. Advantages of indexes: 1. Through Create a unique index to ensure the uniqueness of each row of data in the database table 2. Greatly speed up data query 3. When using grouping and sorting for data query, it can significantly reduce the time of grouping and sorting in the query Disadvantages of index: 1. Maintenance Indexes require database resources. 2. Indexes require disk space. Index files may reach the maximum file size faster than data files. 3. When adding, deleting, or modifying table data, the index needs to be maintained

1. MySQL Optimization - Index specific code analysis

##Introduction: Index is stored implemented in the engine, so the indexes of each storage engine are not necessarily exactly the same, and each storage engine does not necessarily support all index types. Define the maximum number of indexes and maximum index length for each table according to the storage engine. All storage engines support at least 16 indexes per table, with a total index length of at least 256 bytes. Most storage engines have higher limits. There are two storage types of indexes in MYSQL: BTREE and HASH, which are specifically related to the storage engine of the table; MYISAM and InnoDB storage engines only support BTREE indexes;

2. MySQL A detailed introduction to the index length issue of the index

Details of calculating index length in MySQL

##Introduction: First, let’s look at a question. For table t, it contains three fields a, b, c. Assuming that their default values ​​​​are not empty, now create a combined index index (a, b, c) analysis What is the difference between select * from t where a=1 and c=1 and select * from t where a=1 and b=1? First, create a table and execute these two statements respectively. It is found that the difference between the two statements mainly lies in key_len. Why are the differences between the two statements different? My understanding

4.

##Introduction: MySQL MyIsam storage engine When creating an index, there is a strict length limit on the index key length. The sum of the maximum lengths of all index keys cannot exceed 1000, and it is not the sum of the actual data lengths, but the sum of the defined lengths of the index key fields. Let’s do a simple test and record it. root@sky:~# mysql -u sky -p -h127.0

5. Lift the full-text index restriction of mysql

Introduction: Mysql 4.0 has supported the full-text index function, but the default minimum index length of Mysql is 4. For English, this setting is reasonable, but for Chinese or Japanese, this setting is very unreasonable. so, modify the configuration of mysql (my.cnf file): Add a line fft_min_word_len = n after [mysqld] n n is a number less than 4

6. MySql Directory (2)

Introduction: MySql index (2) Reprinted from: http://www.cnblogs.com/dreamhome/archive/2013/04/16/3025304.html All MySQL columns Types can be indexed. Define the maximum number of indexes and maximum index length for each table according to the storage engine. All storage engines support at least 16 indexes per table, with a total index length of at least 256 bytes. Most storage references

7. mysql index length tips innodb and myisam engine_MySQL

Introduction: mysql index length tips innodb and myisam engine

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