5 methods of MySQL paging query

Method 1:

select * from table order by id limit m, n;

It is very simple. The meaning of this statement is to query m+n records, remove the first m records, and return the last n records.There is no doubt that the query can achieve paging, but the larger m, the lower the query performance, because MySQL needs to scan all m+n records.

Method 2:

select * from table where id > #max_id# order by id limit n;

This query will also return the last n records, but it does not need to scan the first m records as in method 1, but must get the maximum id (or minimum id) of the previous query (previous page) in each query,is the more common way.

Of course, the problem with this query is that we may not be able to get this id. For example, if we are currently on page 3 and need to query the data on page 5, it will not work.

Method 3:

In order to avoid cross-page query that cannot be achieved by way 2, it is necessary to combine way 1.

For performance needs, m should be as small as possible.For example, currently on page 3, you need to query page 5, each page has 10 pieces of data, and the current maximum id of page 3 is #max_id#, then:

select * from table where id > #max_id# order by id limit 10, 10;

This method partially solves the problem of method 2, but if it is currently on page 2 and needs to check page 1000, the performance is still poor.

Method 4:

select * from table as a inner join (select id from table order by id limit m, n) as b on a.id = b.id order by a.id;

This query is the same as mode 1, the value of m may be very large, but because the internal subquery only scans the id field instead of the whole table, the performance is stronger than that of mode 1, and it can solve the problem of cross-page query.

Method 5:

select * from table where id > (select id from table order by id limit m, 1) limit n;

This query also scans the field id through a subquery, and the effect is the same as method 4.However, the performance of method 5 is slightly better than that of method 4, because it does not require table association, but a simple comparison, which is a recommended usage without knowing the maximum id of the previous page.

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