## MySQLTuner Internals

## Table of contents

- MySQLTuner Internals
- Table of contents
- MySQLTuner steps
- MySQLTuner get login information steps
- MySQLTuner system checks
- MySQLTuner Server version checks
- Mysql error log file analysis
- MySQL Storage engine general information
- MySQLTuner security checks
- MySQLTuner CVE vulnerabilities detection
- MySQLTuner database information
- MySQLTuner index information
- MySQLTuner Connections information
- MySQLTuner server information
- MySQLTuner sort, join and temp table information
- MySQLTuner global buffer information
- MySQLTuner query cache checks
- MySQLTuner memory checks
- MySQLTuner slow queries checks
- MySQLTuner replication checks
- MySQLTuner InnoDB information
- MySQLTuner ARIADB information
- MySQLTuner MYISAM information
- MySQLTuner Galera information
- MySQLTuner TokuDB information
- MySQLTuner XtraDB information
- MySQLTuner Connect information
- MySQLTuner Spider information
- MySQLTuner RocksDb information
- MySQLTuner Thread pool information
- MySQLTuner performance schema and sysschema information

## MySQLTuner steps

- Header Print
- Get login information
- Set up some OS variables
- Toss variables/status into hashes
- Get information about the tuning connection
- Check current MySQL version
- Suggest 64-bit upgrade
- Analyze mysqld error log file
- Show enabled storage engines
- Show informations about databases (option: –dbstat)
- Show informations about indexes (option: –idxstat)
- Display some security recommendations
- Calculate everything we need
- Print the server stats
- Print MyISAM stats
- Print InnoDB stats
- Print AriaDB stats
- Print replication info
- Make recommendations based on stats
- Close reportfile if needed
- Dump result if debug is on

## MySQLTuner get login information steps

- Is a login possible?
  - Force socket?
  - Remote connection?
    - Specifying available RAM is required
  - Got user/pass on command line?
  - mysql-quickbackup credentials available?
  - Plesk credentials available?
  - DirectAdmin credentials available?
  - Debian maintenance account credentials available?
  - Just try a login
    - If working, and .my.cnf isn’t there, WARNING
    - If working, and .my.cnf is there, okay
  - Prompt for creds on the console

## MySQLTuner system checks

- Check whether more than 2GB RAM present if on 32-bit OS
- Check number of opened ports (warn when more than 9 ports opened)
- Check 80, 8080, 443 and 8443 ports if warning is raised if they are opened
- Check if some banned ports are not opened (option –bannedports separated by comma)
- Check if non kernel and user process except mysqld are not using more than 15% of total physical memory
- Check vm.swapiness
- Check /etc/security/limit.conf
- Check sysctl entries: sunrpc.tcp_slot_entries, vm.swappiness, fs.aio-fs-nr
- Check mount point
- Check Ethernet card
- Check load average

## MySQLTuner Server version checks

- EOL MySQL version check
- Currently MySQL < 5.1 are considered EOL
- Using 5.5+ version of MySQL for performance issue (asynchronous IO)

## Mysql error log file analysis

- Look for potential current error log file name
- Check permission on error log file
- Check size on error log file
- Check error and warning on error log file
- Find last start and shutdown on error log file

## MySQL Storage engine general information

- Get storage engine counts/stats
  - Check for DB engines that are enabled but unused
  - Look for fragmented tables
  - Look for auto-increments near capacity
    - Look for tables with auto-increment with value near max capacity

## MySQLTuner security checks

- Is anonymous user present?
- Users without passwords
- Users with username as password
- Users without host restriction
- Weak password check (possibly using cracklib later?)
- Using basic_passwords.txt as password database
- Password list checks can be avoided (option: –skippassword)

## MySQLTuner CVE vulnerabilities detection

- option: –cvefile
- Check if your MariaDB or MySQL version contains CVE entries.

## MySQLTuner database information

- Performance analysis parameter checks
- Per database information

        * Tables number

  - Rows number
  - Total size
  - Data size
  - Percentage of data size
  - Index size
  - Percentage of index size
    - Collation number
    - Check that there is only one collation for all tables in database
    - Check that there is only one collation for all table columns in database
    - Check that there is only one storage engine per user database

## MySQLTuner index information

- Top 10 worth selectivity index
- Per index information
  - Index Cardinality
  - Index Selectivity
  - Misc information about index definition
  - Misc information about index size

## MySQLTuner Connections information

- Highest usage of available connections
- Percentage of used connections (<85%)
- Percentage of aborted connections (<3%)

## MySQLTuner server information

- Uptime: whether MySQL started within last 24 hours
- Bytes received and sent
- Number of connections
- Percentage between reads and writes
- Is binary log activated?
  - Is GTID mode activated?

## MySQLTuner sort, join and temp table information

- Max memory temporary table size allowed.
- Percentage of sort using temporary table (<10%)
- Number of join performed without using indexes (<250)
- Percentage of temporary table written on disk (<25%)
- Thread cache (=4)
- Thread cache hit ratio (>50%) if thread_handling is different of pools-of-threads
- Table cache hit ratio (>2°%)
- Table cache definition should be upper that total number of tables or in autoresizing mode
- Percentage of open file and open file limit (<85%)
- Percentage of table locks (<95%)
- Percentage of binlog cache lock (<90%)

## MySQLTuner global buffer information

- Key Buffer
- Max Tmp Table
- Per Thread Buffer
  - Read Buffer
  - Read RND Buffer
  - Sort Buffer
  - Thread stack
  - Join Buffer
  - Binlog Cache Buffers size if activated

## MySQLTuner query cache checks

- Is Query cache activated?
  - Query Cache Buffers
  - Query Cache DISABLED, ALL REQUEST or ON DEMAND
  - Query Cache Size
  - Query cache hit ratio (cache efficiency)

## MySQLTuner memory checks

- Get total RAM/swap
- Is there enough memory for max connections reached by MySQL?
- Is there enough memory for max connections allowed by MySQL?
- Max percentage of memory used (<85%)

## MySQLTuner slow queries checks

- Percentage of Slow queries (<5%)

## MySQLTuner replication checks

- Is server replication configured as slave?
- SQL replication thread running?
- IO replication thread running?
- Replication lag in seconds (Seconds_behind_master)
- Is Slave configured in read only?
- Replication type ROW, MIX, STMT
- Replication Semisync master
- Replication Semisync slave
- XA support activated
- Replication started?

## MySQLTuner InnoDB information

- InnoDB Buffer Pool Size
  - If possible, innodb_buffer_pool_size should be greater than data and index size for Innodb Table
  - Innodb_buffer_pool_size should be around 75% to 80% of the available system memory.

- InnoDB Buffer Pool Instances

  - MySQL needs 1 instance per 1Go of Buffer Pool
  - innodb_buffer_pool instances = round(innodb_buffer_pool_size / 1Go)

  - innodb_buffer_pool instances must be equal to or lower than 64

  - A bug in MySQL 5.6 causes SHOW VARIABLES to report an innodb_buffer_pool_instances value of 8 when innodb_buffer_pool_size is less than 1GB and only one buffer pool instance is present (Bug #18343670).

- InnoDB Buffer Pool Usage

  - If more than 20% of InnoDB buffer pool is not used, raise an alert.
- InnoDB Buffer Pool Log Size
  - InnoDB total log file size should be 25% of innodb_buffer_pool_size
- InnoDB Read efficiency
  - Ratio of read without locks
- InnoDB Write efficiency
  - Ratio of write without locks
- InnoDB Log Waits
  - Checks that no lock is used on Innodb Log.
- InnoDB Chunk Size
  - Check InnoDB Buffer Pool size is a multiple of InnoDB Buffer Pool chunk size * InnoDB Buffer Pool instances

## MySQLTuner AriaDB information

- Is Aria indexes size greater than page cache size?
- Page cache read hit ratio (>95%)
- Page cache write hit ratio (>95%)

## MySQLTuner MyISAM information

- Key buffer usage (>90%)
- Is MyISAM indexes size is greater than key buffer size ?
- Key buffer read hit ratio (>95%)
- Key buffer write hit ratio (>95%)

## MySQLTuner Galera information

- wsrep_ready cluster is ready
- wsrep_connected node is connected to other nodes
- wsrep_cluster_name is defined.
- wsrep_node_name is defined.
- Check thet notification script wsrep_notify_cmd is defined
- wsrep_cluster_status PRIMARY /NON PRIMARY.
  - PRIMARY : Coherent cluster
  - NO PRIMARY : cluster gets several states
- wsrep_ local_state_comment: Node state
  - SYNCED (uptodate),
  - DONOR (sending information to another node)
  - Joiner (try to reach cluster group)
  - SYNCED state able to read/write
- wsrep_cluster_conf_id configuration level must be identical in all nodes
- wsrep_slave_thread is between 3 or 4 times number of CPU core.
- gcs.limit should be equal to wsrep_slave_threads * 5
- gcs.fc_factor should be equal to 0.8
- Flow control fraction should be lower than 0.02 (wsrep_flow_control_paused < 0.02)
- wsrep_last_commited committed level must be identical in all nodes
- Look for tables without primary keys
- Look for non InnoDB tables for Galera
- Variable innodb_flush_log_at_trx_commit should be set to 0.
- Check that there are 3 or 5 members in Galera cluster.
- Check that xtrabackup is used for SST method with wsrep_sst_method variable.
- Check variables wsrep_OSU_method is defined to TOI for updates.
- Check that there is no certification failures controlling wsrep_local_cert_failures status.

## MySQLTuner TokuDB information

- tokudb_cache_size
- tokudb_directio
- tokudb_empty_scan
- tokudb_read_block_size
- tokudb_commit_sync
- tokudb_checkpointing_period
- tokudb_block_size
- tokudb_cleaner_iterations
- tokudb_fanout

## MySQLTuner XtraDB information

- Not implemented

## MySQLTuner Connect information

- Not implemented

## MySQLTuner Spider information

- Not implemented

## MySQLTuner RocksDb information

- Not implemented

## MySQLTuner Thread pool information

- thread_pool_size between 16 to 36 for Innodb usage
- thread_pool_size between 4 to 8 for MyISAM usage

## MySQLTuner performance schema and sysschema information

- Check that Performance schema is activated for 5.6+ version
- Check that Performance schema is deactivated for 5.5- version
- Check that Sys schema is installed
- Sys Schema version
- Top user per connection
- Top user per statement
- Top user per statement latency
- Top user per lock latency
- Top user per full scans
- Top user per row_sent
- Top user per row modified
- Top user per io
- Top user per io latency
- Top host per connection
- Top host per statement
- Top host per statement latency
- Top host per lock latency
- Top host per full scans
- Top host per rows sent
- Top host per rows modified
- Top host per io
- Top 5 host per io latency
- Top IO type order by total io
- Top IO type order by total latency
- Top IO type order by max latency
- Top Stages order by total io
- Top Stages order by total latency
- Top Stages order by avg latency
- Top host per table scans
- InnoDB Buffer Pool by schema
- InnoDB Buffer Pool by table
- Process per allocated memory
- InnoDB Lock Waits
- Threads IO Latency
- High Cost SQL statements
- Top 5% slower queries
- Top 10 nb statement type
- Top statement by total latency
- Top statement by lock latency
- Top statement by full scans
- Top statement by rows sent
- Top statement by rows modified
- Use temporary tables
- Unused Indexes
- Full table scans
- Latest file IO by latency
- File by IO read bytes
- File by IO written bytes
- File per IO total latency
- File per IO read latency
- File per IO write latency
- Event Wait by read bytes
- Event Wait by write bytes
- Event per wait total latency
- Event per wait read latency
- Event per wait write latency
- Top 15 most read indexes
- Top 15 most modified indexes
- Top 15 high select latency index
- Top 15 high insert latency index
- Top 15 high update latency index
- Top 15 high delete latency index
- Top 15 most read tables
- Top 15 most modified tables
- Top 15 high select latency tables
- Top 15 high insert latency tables
- Top 15 high update latency tables
- Top 15 high delete latency tables
- Redundant indexes
- Tables not using InnoDb buffer
- Top 15 Tables using InnoDb buffer
- Top 15 Tables with InnoDb buffer free
- Top 15 Most executed queries
- Latest SQL queries in errors or warnings
- Top 20 queries with full table scans
- Top 15 reader queries (95% percentile)
- Top 15 row look queries (95% percentile)
- Top 15 total latency queries (95% percentile)
- Top 15 max latency queries (95% percentile)
- Top 15 average latency queries (95% percentile)
- Top 20 queries with sort
- Last 50 queries with sort
- Top 15 row sorting queries with sort
- Top 15 total latency queries with sort
- Top 15 merge queries with sort
- Top 15 average sort merges queries with sort
- Top 15 scans queries with sort
- Top 15 range queries with sort
- Top 20 queries with temp table
- Last 50 queries with temp table
- Top 15 total latency queries with temp table
- Top 15 queries with temp table to disk
- Top 15 class events by number
- Top 30 events by number
- Top 15 class events by total latency
- Top 30 events by total latency
- Top 15 class events by max latency
- Top 30 events by max latency