我的应用适用于 LAMP 7.3、MySQL 5.7、Cloud VPS。VPS 有 2 GB RAM、1 个 vCPU、60 GB SSD。
MySQL Tuner 工作了 5-6 天，我将分享输出。
-------- Storage Engine Statistics -----------------------------------------------------------------
[--] Status: +ARCHIVE +BLACKHOLE +CSV -FEDERATED +InnoDB +MEMORY +MRG_MYISAM +MyISAM +PERFORMANCE_SCHEMA
[--] Data in MyISAM tables: 35.5K (Tables: 6)
[--] Data in InnoDB tables: 1.3G (Tables: 307)
[OK] Total fragmented tables: 0
-------- Analysis Performance Metrics --------------------------------------------------------------
[--] innodb_stats_on_metadata: OFF
[OK] No stat updates during querying INFORMATION_SCHEMA.
-------- Security Recommendations ------------------------------------------------------------------
[!!] User 'DB_USR@%' does not specify hostname restrictions.
[!!] There is no basic password file list!
-------- CVE Security Recommendations --------------------------------------------------------------
[--] Skipped due to --cvefile option undefined
-------- Performance Metrics -----------------------------------------------------------------------
[--] Up for: 3d 15h 10m 22s (63M q [201.537 qps], 174K conn, TX: 87G, RX: 18G)
[--] Reads / Writes: 97% / 3%
[--] Binary logging is disabled
[--] Physical Memory : 2.0G
[--] Max MySQL memory : 6.0G
[--] Other process memory: 0B
[--] Total buffers: 234.0M global + 39.2M per thread (151 max threads)
[--] P_S Max memory usage: 0B
[--] Galera GCache Max memory usage: 0B
[!!] Maximum reached memory usage: 1.8G (92.22% of installed RAM)
[!!] Maximum possible memory usage: 6.0G (308.25% of installed RAM)
[!!] Overall possible memory usage with other process exceeded memory
[OK] Slow queries: 0% (0/63M)
[OK] Highest usage of available connections: 27% (41/151)
[OK] Aborted connections: 0.00% (1/174710)
[!!] Query cache may be disabled by default due to mutex contention.
[OK] Query cache efficiency: 66.2% (41M cached / 62M selects)
[!!] Query cache prunes per day: 4956861
[OK] Sorts requiring temporary tables: 0% (8K temp sorts / 4M sorts)
[!!] Joins performed without indexes: 69476
[OK] Temporary tables created on disk: 9% (598K on disk / 6M total)
[OK] Thread cache hit rate: 99% (41 created / 174K connections)
[!!] Table cache hit rate: 2% (2K open / 85K opened)
[OK] table_definition_cache(1000) is upper than number of tables(592)
[OK] Open file limit used: 0% (10/5K)
[OK] Table locks acquired immediately: 100% (3K immediate / 3K locks)
-------- Performance schema ------------------------------------------------------------------------
[--] Performance schema is disabled.
[--] Memory used by P_S: 0B
[--] Sys schema is installed.
-------- ThreadPool Metrics ------------------------------------------------------------------------
[--] ThreadPool stat is disabled.
-------- MyISAM Metrics ----------------------------------------------------------------------------
[!!] Key buffer used: 18.3% (1M used / 8M cache)
[OK] Key buffer size / total MyISAM indexes: 8.0M/55.0K
[OK] Read Key buffer hit rate: 97.0% (2K cached / 81 reads)
-------- InnoDB Metrics ----------------------------------------------------------------------------
[--] InnoDB is enabled.
[--] InnoDB Thread Concurrency: 0
[OK] InnoDB File per table is activated
[!!] InnoDB buffer pool / data size: 128.0M/1.3G
[!!] Ratio InnoDB log file size / InnoDB Buffer pool size (75 %): 48.0M * 2/128.0M should be equal to 25%
[OK] InnoDB buffer pool instances: 1
[--] Number of InnoDB Buffer Pool Chunk : 1 for 1 Buffer Pool Instance(s)
[OK] Innodb_buffer_pool_size aligned with Innodb_buffer_pool_chunk_size & Innodb_buffer_pool_instances
[OK] InnoDB Read buffer efficiency: 99.91% (5695188248 hits/ 5700073111 total)
[!!] InnoDB Write Log efficiency: 83.88% (2772762 hits/ 3305708 total)
[OK] InnoDB log waits: 0.00% (0 waits / 532946 writes)
-------- AriaDB Metrics ----------------------------------------------------------------------------
[--] AriaDB is disabled.
-------- TokuDB Metrics ----------------------------------------------------------------------------
[--] TokuDB is disabled.
-------- XtraDB Metrics ----------------------------------------------------------------------------
[--] XtraDB is disabled.
-------- Galera Metrics ----------------------------------------------------------------------------
[--] Galera is disabled.
-------- Replication Metrics -----------------------------------------------------------------------
[--] Galera Synchronous replication: NO
[--] No replication slave(s) for this server.
[--] Binlog format: ROW
[--] XA support enabled: ON
[--] Semi synchronous replication Master: Not Activated
[--] Semi synchronous replication Slave: Not Activated
[--] This is a standalone server
并且有一般性建议：
-------- Recommendations ---------------------------------------------------------------------------
Control warning line(s) into /opt/bitnami/mysql/data/mysqld.log file
Control error line(s) into /opt/bitnami/mysql/data/mysqld.log file
Restrict Host for 'DB_USR'@% to DB_USR@SpecificDNSorIp
UPDATE mysql.user SET host ='SpecificDNSorIp' WHERE user='DB_USR' AND host ='%'; FLUSH PRIVILEGES;
Reduce your overall MySQL memory footprint for system stability
Dedicate this server to your database for highest performance.
We will suggest raising the 'join_buffer_size' until JOINs not using indexes are found.
See https://dev.mysql.com/doc/internals/en/join-buffer-size.html
(specially the conclusions at the bottom of the page).
Increase table_open_cache gradually to avoid file descriptor limits
Read this before increasing table_open_cache over 64:
Read this before increasing for MariaDB https://mariadb.com/kb/en/library/optimizing-table_open_cache/
This is MyISAM only table_cache scalability problem, InnoDB not affected.
See more details here: https://bugs.mysql.com/bug.php?id=49177
This bug already fixed in MySQL 5.7.9 and newer MySQL versions.
Beware that open_files_limit (5000) variable
should be greater than table_open_cache (2100)
Performance schema should be activated for better diagnostics
Before changing innodb_log_file_size and/or innodb_log_files_in_group read this:
Variables to adjust:
*** MySQL's maximum memory usage is dangerously high ***
*** Add RAM before increasing MySQL buffer variables ***
query_cache_size (=0)
query_cache_type (=0)
query_cache_size (> 50M)
join_buffer_size (> 2.0M, or always use indexes with JOINs)
table_open_cache (> 2100)
performance_schema = ON enable PFS
innodb_buffer_pool_size (>= 1.3G) if possible.
innodb_log_file_size should be (=16M) if possible, so InnoDB total log files size equals to 25% of buffer pool size.
和
atop -d输出如下：
它发出红色警报。
SWP | tot 0.0M | free 0.0M | | | | | | | vmcom 1.4G | vmlim 1.0G |
mytop输出是
Cannot connect to MySQL server. Please check the:
* database you specified "" (default is "")
* username you specified "root" (default is "root")
* password you specified "" (default is "")
* hostname you specified "localhost" (default is "localhost")
* port you specified "3306" (default is 3306)
* socket you specified "" (default is "")
The options my be specified on the command-line or in a ~/.mytop or
~/.my.cnf config file. See the manual (perldoc mytop) for details.
Here's the exact error from DBI. It might help you debug:
Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
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谢谢！