I didn't expect that the index occupies several times as much space as the data MySQL queries the space occupied by each table in the database, and the space occupied by data and indexes. It is used i

Paste a picture first ！

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First step ,“ Very important ”

stay mysql in , There is a library built in at the beginning of creation information_schema, This library contains database related information , The space occupied by querying data is to use the library , So first enter this library

--  First of all to enter mysql System libraries 
use information_schema;

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The second step ： Inquire about

Use sum(DATA_LENGTH/1024/1024) Statistical occupancy MB size , It's divided into two parts , One is DATA_LENGTH— data 、INDEX_LENGTH— Indexes .

as follows ：

--  Querying all data in the database takes up space 
SELECT
	concat( round( sum( DATA_LENGTH / 1024 / 1024 ), 2 ), 'MB' ) AS DATA 
FROM
	TABLES;

--  The query   database   Of   Designated table   Data takes up space 
SELECT
	concat( round( sum( data_length / 1024 / 1024 ), 2 ), 'MB' ) AS DATA 
FROM
TABLES 
WHERE
	table_schema = '{your database}' 
	AND table_name = '{your table name}';

--  The query   database   Of   Designated table   Index takes up space 
SELECT
	concat( round( sum( index_length / 1024 / 1024 ), 2 ), 'MB' ) AS DATA 
FROM
TABLES 
WHERE
	table_schema = '{your database}' 
	AND table_name = '{your table name}';

The third step ： Use immediately

Two polished sql, You can directly and clearly query library and The size of the table . Just change the parameters {your databse} that will do
PS： The first step must be performed first

--  Query the sum of all tables in the library , Itemized 
select  
table_schema as ' database ',  
sum(table_rows) as ' Record number ',  
sum(truncate(data_length/1024/1024, 2)) as ' Data capacity (MB)',  
sum(truncate(index_length/1024/1024, 2)) as ' Index capacity (MB)'  
from information_schema.tables  
where table_schema='{your database}'; 

--  The space occupied by each table in the Query Library , Itemized 
select  
table_schema as ' database ',  
table_name as ' Table name ',  
table_rows as ' Record number ',  
truncate(data_length/1024/1024, 2) as ' Data capacity (MB)',  
truncate(index_length/1024/1024, 2) as ' Index capacity (MB)'  
from information_schema.tables  
where table_schema='{your database}'  
order by data_length desc, index_length desc;