概述
今天分享幾個mysql語句,用于日常mysql資料庫的維護和性能診斷!
01 死鎖檢查語句
SELECT
r.trx_id waiting_trx_id,
r.trx_mysql_thread_id waiting_thread,
r.trx_query waiting_query,
b.trx_id blocking_trx_id,
b.trx_mysql_thread_id blocking_thread,
b.trx_query blocking_query
FROM information_schema.innodb_lock_waits w
INNER JOIN information_schema.innodb_trx b
ON b.trx_id = w.blocking_trx_id
INNER JOIN information_schema.innodb_trx r
ON r.trx_id = w.requesting_trx_id;
02 查詢沒有PK定義的表
SELECT
CONCAT('The B-Tree NOT UNIQUE index ', IDX_PREFIX, ' is prefix of the composed index ', IDX_COMPOSED) AS Message,
CONCAT(TABLE_SCHEMA, '.', TABLE_NAME) AS FULL_TABLE_NAME,
IDX_PREFIX,
C_IDX_PREFIX,
IDX_COMPOSED,
C_IDX_COMPOSED
FROM
(
SELECT
TABLE_SCHEMA,
TABLE_NAME,
INDEX_NAME AS 'IDX_PREFIX',
GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX) AS C_IDX_PREFIX
FROM
information_schema.STATISTICS
WHERE TABLE_SCHEMA NOT IN ('mysql', 'sys', 'INFORMATION_SCHEMA', 'PERFORMANCE_SCHEMA')
AND INDEX_TYPE='BTREE'
AND NON_UNIQUE=1
GROUP BY
TABLE_SCHEMA,
TABLE_NAME,
INDEX_NAME
) AS idx1
INNER JOIN
(
SELECT
TABLE_SCHEMA,
TABLE_NAME,
INDEX_NAME AS 'IDX_COMPOSED',
GROUP_CONCAT(COLUMN_NAME ORDER BY SEQ_IN_INDEX) AS C_IDX_COMPOSED
FROM
information_schema.STATISTICS
WHERE INDEX_TYPE='BTREE'
GROUP BY
TABLE_SCHEMA,
TABLE_NAME,
INDEX_NAME
) AS idx2
USING (TABLE_SCHEMA, TABLE_NAME)
WHERE idx1.C_IDX_PREFIX != idx2.C_IDX_COMPOSED AND LOCATE(CONCAT(idx1.C_IDX_PREFIX, ','), idx2.C_IDX_COMPOSED) = 1;
03 查詢DB的空間占用
select
sum(data_length)/1024/1024 as data_lenght_mb,
sum(data_free)/1024/1024 as data_free_mb,
sum(index_length)/1024/1024 as index_lenght_mb,
(select (@@innodb_log_files_in_group * @@innodb_log_file_size)/1024/1024) as innodb_log_size_mb,
(sum(data_length)+sum(data_free)+sum(index_length)+(select (@@innodb_log_files_in_group * @@innodb_log_file_size)))/1024/1024 as tot_mb
from
information_schema.tables;
04 查詢有自增主鍵的表
select
t.table_catalog,
t.table_schema,
t.table_name,
c.column_name,
c.data_type,
c.column_type,
t.auto_increment,
(case c.data_type
when 'tinyint' THEN 255
when 'smallint' THEN 65535
when 'mediumint' THEN 16777215
when 'int' THEN 4294967295
when 'bigint' THEN 18446744073709551615
end >> if(LOCATE('unsigned', c.column_type) > 0, 0, 1)) as max_value
from information_schema.tables t inner join information_schema.columns c
on t.table_name = c.table_name and c.table_catalog = t.table_catalog and c.table_schema = t.table_schema
where c.extra = 'auto_increment' AND
t.table_schema NOT IN ('mysql', 'information_schema', 'performance_schema','sys')
order by t.auto_increment desc;
05 查詢沒有自增主鍵的表
select
t.table_catalog,
t.table_schema,
t.table_name,
c.column_name,
c.data_type,
c.column_type,
(case c.data_type
when 'tinyint' THEN 255
when 'smallint' THEN 65535
when 'mediumint' THEN 16777215
when 'int' THEN 4294967295
when 'bigint' THEN 18446744073709551615
end >> if(LOCATE('unsigned', c.column_type) > 0, 0, 1)) as max_value
from
information_schema.tables t inner join information_schema.columns c
on t.table_name = c.table_name and c.table_catalog = t.table_catalog and c.table_schema = t.table_schema
where c.extra != 'auto_increment' AND
t.table_schema NOT IN ('mysql', 'information_schema', 'performance_schema','sys') AND
c.data_type in ('tinyint', 'int', 'mediumint', 'bigint')
;
06 查詢有PK定義的表
SELECT
t2.TABLE_SCHEMA,
t2.TABLE_NAME,
t2.ENGINE
FROM
information_schema.TABLES t2,
(
SELECT
t.TABLE_SCHEMA,
t.TABLE_NAME
FROM
information_schema.COLUMNS c,
information_schema.TABLES t
WHERE t.TABLE_SCHEMA not in ('mysql','sys')
AND c.TABLE_NAME=t.TABLE_NAME
AND c.TABLE_SCHEMA=t.TABLE_SCHEMA
AND c.COLUMN_KEY='PRI'
GROUP BY
t.TABLE_SCHEMA,
t.TABLE_NAME
) pkt
WHERE t2.TABLE_SCHEMA not in ('mysql','sys','INFORMATION_SCHEMA','PERFORMANCE_SCHEMA')
AND (t2.TABLE_SCHEMA=pkt.TABLE_SCHEMA AND t2.TABLE_NAME=pkt.TABLE_NAME);
07 查詢有PK表定義的列名資訊
SELECT
t.TABLE_SCHEMA,
t.TABLE_NAME,
t.ENGINE,
c.COLUMN_NAME as PK
FROM
information_schema.COLUMNS c,
information_schema.TABLES t
WHERE t.TABLE_SCHEMA not in ('mysql','sys')
AND c.TABLE_NAME=t.TABLE_NAME
AND c.TABLE_SCHEMA=t.TABLE_SCHEMA
AND c.COLUMN_KEY='PRI'
;