MySQL optimization (vi)

26. How to know the MySQL to solve a query

Run the Item column command and try to figure out its output:

Show VARIABLES;

Show COLUMNS from ... G

EXPLAIN SELECT ... G

FLUSH STATUS;

SELECT ...;

Show STATUS;

27, MySQL is very good

Log

When many connections are made, the connection is very fast.

Use both Select and insert situations.

When you don't combine updates with too long a choice.

When most selections/updates use unique key codes.

When you use multiple tables that do not have long conflicting locks.

When using a large table (MySQL uses a very compact tabular format).

28, MySQL should avoid things

Updates or inserts a table with a deleted row, combining a select that takes a long time.

Use a having on a column that can be placed in a WHERE clause.

Join without the use of a key or key code that is not unique.

Joins on columns of different column types.

Use the heap table when you do not use = match the entire key code.

Forget to use a WHERE clause in the update or delete in the MySQL monitor. If you want to do this, use the--i-am-a-dummy option for the MySQL client program.