Mysql Late row lookups (delayed row lookup)

Mysql Late row lookups (delayed row lookup) SQL code CREATE TABLE '201430122handler' ('id' int (11) NOT NULL AUTO_INCREMENT, 'uid' int (11) NOT NULL, 'content' varchar (50) not null, primary key ('id'), KEY '3030122handler _ idx_uid '('uid') ENGINE = InnoDB www.2cto.com contains 60 million data, now the simulation of paging by uid depends on the content on the seventh page. Use the SQL code select SQL _NO_CACHE * from 20130122 handler order by uid LIMIT, 20 to find 20 pieces of data, it is basically an instant thing. Assume that the user is abnormal. Click page 102 and use the SQL code select SQL _NO_CACHE * from 20130122 handler order by uid LIMIT 20,20 www.2cto.com to find 20 pieces of data, it seems that the performance is quite poor. In this case, mysql reads 2040 secondary records from the 20130122handler_idx_uid index, runs 2040 primary key queries, and returns 20 records, therefore, 2020 primary key queries are wasted. You can use this method to reduce useless row lookup SQL code select SQL _NO_CACHE m. * from (select uid from 20130122 handler order by uid LIMIT 2020,20) t, 20130122 handler m where t. uid = m. uid because 20130122handler_idx_uid is a secondary index, so the SQL code select SQL _NO_CACHE * from 20130122 handler order by id LIMIT 120,20 select SQL _NO_CACHE * from 20130122 handler ORDER BY id LIMIT 2040,20 is not obvious