全球地位
MariaDB [(none)]> SHOW GLOBAL STATUS;
+--------------------------------------------------------------+--------------------------------------------------+
| Variable_name | Value |
+--------------------------------------------------------------+--------------------------------------------------+
| Aborted_clients | 10 |
| Aborted_connects | 17 |
| Access_denied_errors | 2808 |
| Acl_column_grants | 0 |
| Acl_database_grants | 255 |
| Acl_function_grants | 0 |
| Acl_procedure_grants | 0 |
| Acl_proxy_users | 1 |
| Acl_role_grants | 0 |
| Acl_roles | 0 |
| Acl_table_grants | 2 |
| Acl_users | 253 |
| Aria_pagecache_blocks_not_flushed | 0 |
| Aria_pagecache_blocks_unused | 15706 |
| Aria_pagecache_blocks_used | 40 |
| Aria_pagecache_read_requests | 287044 |
| Aria_pagecache_reads | 20253 |
| Aria_pagecache_write_requests | 36614 |
| Aria_pagecache_writes | 36593 |
| Aria_transaction_log_syncs | 1 |
| Binlog_commits | 0 |
| Binlog_group_commits | 0 |
| Binlog_group_commit_trigger_count | 0 |
| Binlog_group_commit_trigger_lock_wait | 0 |
| Binlog_group_commit_trigger_timeout | 0 |
| Binlog_snapshot_file | |
| Binlog_snapshot_position | 0 |
| Binlog_bytes_written | 0 |
| Binlog_cache_disk_use | 0 |
| Binlog_cache_use | 0 |
| Binlog_stmt_cache_disk_use | 0 |
| Binlog_stmt_cache_use | 0 |
| Busy_time | 0.000000 |
| Bytes_received | 243371501 |
| Bytes_sent | 2355355672 |
| Com_admin_commands | 2293 |
| Com_alter_db | 0 |
| Com_alter_db_upgrade | 0 |
| Com_alter_event | 0 |
| Com_alter_function | 0 |
| Com_alter_procedure | 0 |
| Com_alter_server | 0 |
| Com_alter_table | 0 |
| Com_alter_tablespace | 0 |
| Com_alter_user | 0 |
| Com_analyze | 0 |
| Com_assign_to_keycache | 0 |
| Com_begin | 0 |
| Com_binlog | 0 |
| Com_call_procedure | 0 |
| Com_change_db | 92 |
| Com_change_master | 0 |
| Com_check | 0 |
| Com_checksum | 0 |
| Com_commit | 0 |
| Com_compound_sql | 0 |
| Com_create_db | 0 |
| Com_create_event | 0 |
| Com_create_function | 0 |
| Com_create_index | 0 |
| Com_create_procedure | 0 |
| Com_create_role | 0 |
| Com_create_server | 0 |
| Com_create_table | 0 |
| Com_create_temporary_table | 0 |
| Com_create_trigger | 0 |
| Com_create_udf | 0 |
| Com_create_user | 0 |
| Com_create_view | 0 |
| Com_dealloc_sql | 0 |
| Com_delete | 8354 |
| Com_delete_multi | 0 |
| Com_do | 0 |
| Com_drop_db | 0 |
| Com_drop_event | 0 |
| Com_drop_function | 0 |
| Com_drop_index | 0 |
| Com_drop_procedure | 0 |
| Com_drop_role | 0 |
| Com_drop_server | 0 |
| Com_drop_table | 0 |
| Com_drop_temporary_table | 0 |
| Com_drop_trigger | 0 |
| Com_drop_user | 0 |
| Com_drop_view | 0 |
| Com_empty_query | 0 |
| Com_execute_immediate | 0 |
| Com_execute_sql | 0 |
| Com_flush | 0 |
| Com_get_diagnostics | 0 |
| Com_grant | 0 |
488 rows in set (0.00 sec)
MariaDB [(none)]>
我的cnf
[root@host ~]# cat /etc/my.cnf
#
# This group is read both both by the client and the server
# use it for options that affect everything
#
[client-server]
#
# include all files from the config directory
#
!includedir /etc/my.cnf.d
[mysqld]
log-error=/var/lib/mysql/s102.halabtech.net.err
performance-schema=0
innodb_file_per_table=1
default-storage-engine=MyISAM
max_allowed_packet=268435456
open_files_limit=40000
skip-name-resolve
sql_mode=''
local-infile=0
connect_timeout=25
wait_timeout=30
interactive_timeout=30
slow-query-log=1
long_query_time=5
slow_query_log_file="/var/log/mysql-slow.log"
key_buffer_size = 128M
thread_stack = 128K
thread_cache_size = 8
max_heap_table_size = 256M
query_cache_limit = 4M
query_cache_size = 512M
innodb_buffer_pool_size = 2G
服务器规格:
Intel(R) Core(TM) i7-8700 CPU @ 3.20GHz
Memory: 4107488k/68927488k available (7792k kernel code, 1900528k absent, 1353716k reserved, 5950k data, 1984k init)
Filesystem Size Used Avail Use% Mounted on
devtmpfs 32G 0 32G 0% /dev
tmpfs 32G 0 32G 0% /dev/shm
tmpfs 32G 28M 32G 1% /run
tmpfs 32G 0 32G 0% /sys/fs/cgroup
/dev/md2 437G 273G 142G 66% /
/dev/md1 488M 401M 62M 87% /boot
tmpfs 6.3G 0 6.3G 0% /run/user/0
tmpfs 6.3G 0 6.3G 0% /run/user/987
tmpfs 6.3G 0 6.3G 0% /run/user/1034
更新
MYSQL 慢查询转储:(数据库真实姓名已更改)
Reading mysql slow query log from /var/log/mysql-slow.log
Count: 2 Time=20.58s (41s) Lock=0.00s (0s) Rows_sent=4089261.5 (8178523), Rows_examined=4089261.5 (8178523), Rows_affected=0.0 (0), root[root]@localhost
SELECT /*!40001 SQL_NO_CACHE */ * FROM `hb_udownloads`
Count: 3 Time=15.38s (46s) Lock=0.00s (0s) Rows_sent=81.0 (243), Rows_examined=10026558.0 (30079674), Rows_affected=0.0 (0), server***_fusion[server***_fusion]@localhost
SELECT *,(select count(id) from tbl_swkey
where group_id=tbl_keygroup.id and used=0) as selled,(select count(id) from tbl_swkey
where group_id=tbl_keygroup.id and used=1) as used FROM tbl_keygroup
order by `displayorder` asc
Count: 1 Time=8.68s (8s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4090482.0 (4090482), Rows_affected=0.0 (0), support***_res[support***_res]@localhost
UPDATE hb_udownloads SET `upackage_id` = 0 WHERE upackage_id = 403775
Count: 1 Time=5.64s (5s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4088258.0 (4088258), Rows_affected=0.0 (0), support***_res[support***_res]@localhost
SELECT udownload_id AS retval FROM hb_udownloads WHERE user_id = 415064 AND file_id = 78499 LIMIT 1
Count: 1 Time=5.58s (5s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4088256.0 (4088256), Rows_affected=0.0 (0), support***_res[support***_res]@localhost
SELECT udownload_id AS retval FROM hb_udownloads WHERE user_id = 208286 AND file_id = 202629 LIMIT 1
Count: 1 Time=5.35s (5s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4088255.0 (4088255), Rows_affected=0.0 (0), support***_res[support***_res]@localhost
SELECT udownload_id AS retval FROM hb_udownloads WHERE user_id = 235082 AND file_id = 473624 LIMIT 1
Count: 1 Time=5.21s (5s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4088254.0 (4088254), Rows_affected=0.0 (0), support***_res[supporth***_res]@localhost
SELECT udownload_id AS retval FROM hb_udownloads WHERE user_id = 61350 AND file_id = 493488 LIMIT 1
Count: 1 Time=5.17s (5s) Lock=0.00s (0s) Rows_sent=0.0 (0), Rows_examined=4088259.0 (4088259), Rows_affected=0.0 (0), support***_res[support***_res]@localhost
SELECT udownload_id AS retval FROM hb_udownloads WHERE user_id = 338554 AND file_id = 439150 LIMIT 1
请告知为什么我有时会出现高达 500% 的峰值,以及由于我收到大量 50x 错误,应该采取什么措施来解决这个问题。也请原谅我的英语不好。提前谢谢您。
答案1
高 CPU 使用率通常意味着大量的内存表扫描。
查看您的一个慢速查询:
Time=5.64s (5s) Rows_sent=0.0 (0) Rows_examined=4088258.0 (4088258)
SELECT udownload_id AS retval
FROM hb_udownloads
WHERE user_id = 415064
AND file_id = 78499
LIMIT 1
该查询正在读取整个 4M 行表,但最多返回一(在本例中,没有)。
你需要索引在该表上支持该查询。复合的user_id
和file_id
将是一个好的开始。
另一个性能杀手是:
Time=20.58s (41s) Rows_sent=4089261.5 (8178523) Rows_examined=4089261.5 (8178523)
SELECT /*!40001 SQL_NO_CACHE */ *
FROM `hb_udownloads`
切勿使用“选择 *“在生产代码中。
总是明确指定您想要的列。我猜这个表最近一直在“增长”(增加列)。
好吧,如果没有 where 子句,这无论如何都会进行表扫描,但这引出了一个问题 - 可怜的客户端[应用程序]将做什么做这个查询“抛出”了 4M 行数据?
答案2
其中一些查询看起来可能需要优化。
例如:
Rows_examined=10026558.0 (30079674), Rows_affected=0.0 (0), server***_fusion[server***_fusion]@localhost
SELECT *,(select count(id) from tbl_swkey
where group_id=tbl_keygroup.id and used=0) as selled,(select count(id) from tbl_swkey
where group_id=tbl_keygroup.id and used=1) as used FROM tbl_keygroup
order by `displayorder` asc
此查询正在扫描 30000000 行。
您可以将其更改为两个查询:
SELECT * FROM tbl_keygroup ORDER by `displayorder` asc;
SELECT count(id) FROM tbl_swkey WHERE used IN (0,1) GROUP BY used;
因为查询本身涉及无用的连接和两次可以减半的全表扫描。
您所展示的大部分内容都指向查询优化问题,我会查看那个慢速查询日志,以确定以最少的表扫描来检索该数据的最佳方式。
出于同一目的,您可能还想对大量数据进行索引。
答案3
** 这应该会使第一个更快:
SELECT k.*, s.sold, s.used
FROM ( SELECT group_id,
SUM(used = 0) AS sold,
SUM(used = 1) AS used
FROM tbl_swkey
) AS s
JOIN tbl_keygroup AS k ON s.group_id = k.id
ORDER BY displayorder
并且有
tbl_swkey: INDEX(group_id, used)
tbl_keygroup: INDEX(displayorder)
如果您需要进一步讨论此查询,请提供SHOW CREATE TABLE
两个表格、表格大小和EXPLAIN SELECT ...
。
** 这
SELECT udownload_id AS retval
FROM hb_udownloads
WHERE user_id = 415064
AND file_id = 78499
LIMIT 1
需要一个 3 列复合索引才能更快:
INDEX(user_id, file_id, udownload_id)
您不关心获得哪一行匹配?还是应该添加一个ORDER BY
?如果添加一个ORDER BY
,我的索引建议可能需要更改。
** 这是从哪里来的mysqldump
?
SELECT /*!40001 SQL_NO_CACHE */ * FROM `hb_udownloads`
如果您对转储的侵入性感到不满,dba.stackexchange.com 上有几个关于该主题的讨论。