Question

您好，我是数据库新手。我正在研究庞大的数据库并试图清理混乱。我想首先找到占据整个数据库中最高内存的前十个表。由于桌子太多，我无法找到每张桌子的记忆。我需要占据最大空间的前10或20个桌子。任何帮助将非常感激。谢谢。

Answer 1

也许是这样的：

SELECT CONCAT(table_schema, '.', table_name),
       CONCAT(ROUND(table_rows / 1000000, 2), 'M')                                    rows,
       CONCAT(ROUND(data_length / ( 1024 * 1024 * 1024 ), 2), 'G')                    DATA,
       CONCAT(ROUND(index_length / ( 1024 * 1024 * 1024 ), 2), 'G')                   idx,
       CONCAT(ROUND(( data_length + index_length ) / ( 1024 * 1024 * 1024 ), 2), 'G') total_size,
       ROUND(index_length / data_length, 2)                                           idxfrac
FROM   information_schema.TABLES
ORDER  BY data_length + index_length DESC
LIMIT  10;

参考here

Answer 2

MyISAM仅为其索引占用内存

要查找在最坏情况下可以使用最多内存的前10个MyISAM表，请尝试：

SELECT * FROM
(
    SELECT table_schema,table_name,index_length
    FROM information_schema.tables
    WHERE engine='MyISAM' AND
    table_schema NOT IN ('information_schema','mysql','performance_schema')
    ORDER BY index_length DESC
) LIMIT 10;

InnoDB为其数据和索引占用内存

要查找在最坏情况下可以使用最多内存的前10个InnoDB表，请尝试以下方法：

SELECT * FROM
(
    SELECT table_schema,table_name,data_length+index_length tblsize
    FROM information_schema.tables
    WHERE engine='InnoDB'
    ORDER BY index_length DESC
) LIMIT 10;

这是前50个表格按大小递减显示的另一个显示

SELECT * FROM
(SELECT TN TableName,LPAD(REPLACE(FORMAT(TS/POWER(1024,1),2),',',''),Z,' ') KB,
LPAD(REPLACE(FORMAT(TS/POWER(1024,2),2),',',''),Z,' ') MB,
LPAD(REPLACE(FORMAT(TS/POWER(1024,3),2),',',''),Z,' ') GB
FROM (SELECT CONCAT(table_schema,'.',table_name) TN,
(data_length+index_length) TS FROM information_schema.tables
WHERE table_schema NOT IN ('information_schema','mysql','performance_schema')
AND engine IS NOT NULL) A,(SELECT 13 Z) B ORDER BY TS DESC) MMM LIMIT 50;

如果您有兴趣，我会在MySQL实例上提供有关整个故事的查询

此查询显示存储引擎以GB为单位占用的磁盘空间量

SELECT IFNULL(B.engine,'Total') "Storage Engine",
CONCAT(LPAD(REPLACE(FORMAT(B.DSize/POWER(1024,pw),3),',',''),17,' '),
' ',SUBSTR(' KMGTP',pw+1,1),'B') "Data Size",
CONCAT(LPAD(REPLACE(FORMAT(B.ISize/POWER(1024,pw),3),',',''),17,' '),
' ',SUBSTR(' KMGTP',pw+1,1),'B') "Index Size", CONCAT(LPAD(REPLACE(
FORMAT(B.TSize/POWER(1024,pw),3),',',''),17,' '),' ',
SUBSTR(' KMGTP',pw+1,1),'B') "Table Size"
FROM (SELECT engine,SUM(data_length) DSize,SUM(index_length) ISize,
SUM(data_length+index_length) TSize FROM information_schema.tables
WHERE table_schema NOT IN ('mysql','information_schema','performance_schema')
AND engine IS NOT NULL GROUP BY engine WITH ROLLUP) B,(SELECT 3 pw) A ORDER BY TSize;

此查询显示数据库以GB为单位占用的磁盘空间量

SELECT DBName,CONCAT(LPAD(FORMAT(SDSize/POWER(1024,pw),3),17,' '),
' ',SUBSTR(' KMGTP',pw+1,1),'B') "Data Size",CONCAT(LPAD(FORMAT(SXSize/
POWER(1024,pw),3),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B') "Index Size",
CONCAT(LPAD(FORMAT(STSize/POWER(1024,pw),3),17,' '),' ',
SUBSTR(' KMGTP',pw+1,1),'B') "Total Size" FROM
(SELECT IFNULL(DB,'All Databases') DBName,SUM(DSize) SDSize,
SUM(XSize) SXSize,SUM(TSize) STSize FROM (SELECT table_schema DB,
data_length DSize,index_length XSize,data_length+index_length TSize
FROM information_schema.tables WHERE table_schema NOT IN
('mysql','information_schema','performance_schema')) AAA
GROUP BY DB WITH ROLLUP) AA,(SELECT 3 pw) BB ORDER BY (SDSize+SXSize);

此查询显示数据库按存储引擎占用的磁盘空间量（GB）

SELECT IF(ISNULL(B.table_schema)+ISNULL(B.engine)=2,"Storage for All Databases",
IF(ISNULL(B.table_schema)+ISNULL(B.engine)=1,CONCAT("Storage for ",B.table_schema),
CONCAT(B.engine," Tables for ",B.table_schema))) Statistic,CONCAT(LPAD(REPLACE(
FORMAT(B.DSize/POWER(1024,pw),3),',',''),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B')
"Data Size",CONCAT(LPAD(REPLACE(FORMAT(B.ISize/POWER(1024,pw),3),',',''),17,' '),
' ',SUBSTR(' KMGTP',pw+1,1),'B') "Index Size",CONCAT(LPAD(REPLACE(FORMAT(B.TSize/
POWER(1024,pw),3),',',''),17,' '),' ',SUBSTR(' KMGTP',pw+1,1),'B') "Table Size"
FROM (SELECT table_schema,engine,SUM(data_length) DSize,SUM(index_length) ISize,
SUM(data_length+index_length) TSize FROM information_schema.tables WHERE
table_schema NOT IN ('mysql','information_schema','performance_schema')
AND engine IS NOT NULL GROUP BY table_schema,engine WITH ROLLUP) B,
(SELECT 3 pw) A ORDER BY TSize;

我发布的前三个查询有一个共同特征：子查询(SELECT 3 pw)

如果您使用(SELECT 0 pw)，则报告位于字节
如果您使用(SELECT 1 pw)，则报告位于KiloBytes
如果您使用(SELECT 2 pw)，则报告位于MegaBytes
如果您使用(SELECT 3 pw)，则报告位于GigaBytes
如果您使用(SELECT 4 pw)，则报告位于TeraBytes
如果你使用(SELECT 5 pw)，报告是在PetaBytes中（如果你需要，请发布结果!!!）

Answer 3

您可以使用SHOW TABLE STATUS来获取每个表的大小。

Answer 4

这是我在阅读完所有答案后使用的查询。

  SELECT table_name,round((data_length+index_length)/(1024 * 1024 *1024),2) table_size
  FROM information_schema.tables 
  ORDER BY data_length + index_length 
  DESC  limit 10;

如何找出占用数据库最大内存的表？

4 个答案: