MySQL Range Optimization and Multipart index












0















Hi i'm newbie to MySQL World.



When i read about MySQL Range Optimization some of question were raised related to multipart index.



MySQL 5.7 Doc



(http://jorgenloland.blogspot.com/2011/08/mysql-range-access-method-explained.html)



Question 1 :
What is the meaning of single and continuous intervals ?



Question 2 :
Related to Multipart index and keylen



Table Structure
Create table orders(customer_id int,value int,name varchar(20),primary key(customer_id,value)) ;



A)



mysql> explain select * from orders where customer_id  <= 2  and value = 1;

+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
| 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 8 | NULL | 4 | 25.00 | Using where |
+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


B)



mysql> explain select * from orders where customer_id  < 2  and value = 1;

+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
| 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 4 | 25.00 | Using where |
+----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


why explain statement (A) shows keylen as 8 but (B) shows keylen as 4










share|improve this question





























    0















    Hi i'm newbie to MySQL World.



    When i read about MySQL Range Optimization some of question were raised related to multipart index.



    MySQL 5.7 Doc



    (http://jorgenloland.blogspot.com/2011/08/mysql-range-access-method-explained.html)



    Question 1 :
    What is the meaning of single and continuous intervals ?



    Question 2 :
    Related to Multipart index and keylen



    Table Structure
    Create table orders(customer_id int,value int,name varchar(20),primary key(customer_id,value)) ;



    A)



    mysql> explain select * from orders where customer_id  <= 2  and value = 1;

    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
    | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
    | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 8 | NULL | 4 | 25.00 | Using where |
    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


    B)



    mysql> explain select * from orders where customer_id  < 2  and value = 1;

    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
    | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
    | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 4 | 25.00 | Using where |
    +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


    why explain statement (A) shows keylen as 8 but (B) shows keylen as 4










    share|improve this question



























      0












      0








      0








      Hi i'm newbie to MySQL World.



      When i read about MySQL Range Optimization some of question were raised related to multipart index.



      MySQL 5.7 Doc



      (http://jorgenloland.blogspot.com/2011/08/mysql-range-access-method-explained.html)



      Question 1 :
      What is the meaning of single and continuous intervals ?



      Question 2 :
      Related to Multipart index and keylen



      Table Structure
      Create table orders(customer_id int,value int,name varchar(20),primary key(customer_id,value)) ;



      A)



      mysql> explain select * from orders where customer_id  <= 2  and value = 1;

      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 8 | NULL | 4 | 25.00 | Using where |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


      B)



      mysql> explain select * from orders where customer_id  < 2  and value = 1;

      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 4 | 25.00 | Using where |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


      why explain statement (A) shows keylen as 8 but (B) shows keylen as 4










      share|improve this question
















      Hi i'm newbie to MySQL World.



      When i read about MySQL Range Optimization some of question were raised related to multipart index.



      MySQL 5.7 Doc



      (http://jorgenloland.blogspot.com/2011/08/mysql-range-access-method-explained.html)



      Question 1 :
      What is the meaning of single and continuous intervals ?



      Question 2 :
      Related to Multipart index and keylen



      Table Structure
      Create table orders(customer_id int,value int,name varchar(20),primary key(customer_id,value)) ;



      A)



      mysql> explain select * from orders where customer_id  <= 2  and value = 1;

      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 8 | NULL | 4 | 25.00 | Using where |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


      B)



      mysql> explain select * from orders where customer_id  < 2  and value = 1;

      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+
      | 1 | SIMPLE | orders | NULL | range | PRIMARY | PRIMARY | 4 | NULL | 4 | 25.00 | Using where |
      +----+-------------+--------+------------+-------+---------------+---------+---------+------+------+----------+-------------+


      why explain statement (A) shows keylen as 8 but (B) shows keylen as 4







      mysql database mysql-5.7 mysql-5.6 mysql-5.5






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 23 '18 at 13:57







      RKs

















      asked Nov 19 '18 at 16:16









      RKsRKs

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