MySQL Performance: Identifying Long Queries

Posted on by J. Potter | Updated:
Category: Featured Articles, Series | Tags: , , , , , , ,

Every MySQL backed application can benefit from a finely tuned database server. The Liquid Web Heroic Support team has encountered numerous situations over the years where some minor adjustments have made a world of difference in website and application performance. In this series of articles, we have outlined some of the more common recommendations that have had the largest impact on performance.

Preflight Check

This article applies to most Linux based MySQL servers. This includes, but is not limited to, both Traditional Dedicated and Cloud VPS servers running a variety of common Linux distributions. The article can be used with the following Liquid Web system types:

  • Core-managed CentOS 6x/7x
  • Core-managed Ubuntu 14.04/16.04
  • Fully-managed CentOS 6/7 cPanel
  • Fully-managed CentOS 7 Plesk Onyx 17
  • Self-managed Linux servers
Note
Self-managed systems, which have opted out of direct support can take advantage of the techniques discussed here, however, the Liquid Web Heroic Support Team cannot offer direct aid on these server types.

This series of articles assumes familiarity with the following basic system administration concepts:

 

What is MySQL Optimization?

There is no clearly defined definition for the term MySQL Optimization. It can mean something different depending on the person,  administrator, group or company. For the sake of this series of articles on MySQL Optimization, we will define MySQL Optimization as:  The configuration of a MySQL or MariaDB server which has been configured to avoid commonly encountered bottlenecks discussed in this series of articles.

What is a bottleneck?

Very similar to the neck on a soda bottle, a bottleneck as a technical term is a point in an application or server configuration where a small amount of traffic or data can pass through without issue. However, a larger volume of the same type of traffic or data is hindered or blocked and cannot operate successfully as-is. See the following example of a configuration bottleneck:

Visual Difference between Optimized and Non-Optimized DatabaseIn this example, the server is capable of handling 10 connections simultaneously. However, the configuration only accepts 5 connections. This issue would not manifest so long as there were 5 or less connections at one time. However, when traffic ramps up to 10 connections, half of them start to fail due to unused resources in the server configuration. The above examples illustrates the bottleneck shape where it derives its name versus an optimized configuration which corrects the bottleneck.

When Should I Optimize My MySQL database?

Ideally, database performance tuning should occur regularly and before productivity is affected. It is best practice behavior to conduct weekly or monthly audits of database performance to prevent issues from adversely affecting  applications. The most obvious symptoms of performance problems are:

  • Queries stack up and never completing in the MySQL process table.
  • Applications or websites using the database become sluggish.
  • Connection timeouts errors, especially during peak hours.

While it is normal for there to be several concurrent queries running at one time on a busy system, it becomes a problem when these queries are taking too long to finish on a regular basis. Although the specific threshold varies per system and per application, average query times exceeding several seconds will manifest as a slowdown within attached websites and applications. These slowdowns can sometimes start out small and go unnoticed until a large traffic surge hits a particular bottleneck.

Identifying Performance Issues

Knowing how to examine the MySQL process table is vital for diagnosing the specific bottleneck being encountered. There is a number of ways to view the process table depending on your particular server and preference. For the sake of brevity this series will focus on the most common methods used via Secure Shell (SSH) access:

 

Using The MySQL Process Table: Method 1

Use the ‘mysqladmin’ command line tool with the flag ‘processlist’ or ‘proc’ for short. (Adding the flag ‘statistics’ or ‘stat’ for short will show running statistics for queries since MySQL’s last restart.)

Command:

mysqladmin proc stat

Output:

 +-------+------+-----------+-----------+---------+------+-------+
| Id | User | Host | db | Command | Time | State | Info | Progress |
+-------+------+-----------+-----------+---------+------+-------+--------------------+----------+
| 77255 | root | localhost | employees | Query | 150 | | call While_Loop2() | 0.000 |
| 77285 | root | localhost | | Query | 0 | init | show processlist | 0.000 |
+-------+------+-----------+-----------+---------+------+-------+--------------------+----------+
Uptime: 861755 Threads: 2 Questions: 20961045 Slow queries: 0 Opens: 2976 Flush tables: 1 Open tables: 1011 Queries per second avg: 24.323

Pro: Used on the shell interface, this makes piping output to other scripts and tools very easy.
Con: The process table’s info column is always truncated so does not provide the full query on longer queries.

Using The MySQL Process Table: Method 2

Run the ‘show processlist;’ query from within MySQL interactive mode prompt. (Adding the ‘full’  modifier to the command disables truncation of the Info column. This is necessary when viewing long queries.)

 

Command:

show processlist;

Output:
MariaDB [(none)]> show full processlist;
+-------+------+-----------+-----------+---------+------+-------+-----------------------+----------+
| Id | User | Host | db | Command | Time | State | Info | Progress |
+-------+------+-----------+-----------+---------+------+-------+-----------------------+----------+
| 77006 | root | localhost | employees | Query | 151 | NULL | call While_Loop2() | 0.000 |
| 77021 | root | localhost | NULL | Query | 0 | init | show full processlist | 0.000 |
+-------+------+-----------+-----------+---------+------+-------+-----------------------+----------+

Pro: Using the full modifier allows for seeing the full query on longer queries.
Con: MySQL Interactive mode cannot access scripts and tools available in the shell interface.

Using The slow query log

Another valuable tool in  MySQL is the included slow query logging feature. This feature is the preferred method for finding long running queries on a regular basis. There are several directives available to adjust this feature. However, the most commonly needed settings are:

 

slow_query_logenable/disable the slow query log
slow_query_log_filename and path of the slow query log file
long_query_timetime in seconds/microseconds defining a slow query

These directives are set within the [mysqld] section of the MySQL configuration file located at /etc/my.cnf and will require a MySQL service restart before they will take affect. See the example below for formatting:

Caution
There is a large disk space concern with the slow query log file, which needs to be attended to continually until the slow query log feature is disabled. Keep in mind, the lower your long_query_time directive the faster the slow query log fills up a disk partition.
[mysqld]
log-error=/var/lib/mysql/mysql.err
innodb_file_per_table=1
default-storage-engine=innodb
innodb_buffer_pool_size=128M
innodb_log_file_size=128M
max_connections=300
key_buffer_size = 8M
slow_query_log=1
slow_query_log_file=/var/lib/mysql/slowquery.log
long_query_time=5

Once the slow query log is enabled you will need to periodically follow-up with it to review unruly queries that need to be adjusted for better performance. To analyze the slow query log file, you can parse it directly to review its contents. The following example shows the statistics for the sample query which ran longer that the configured 5 seconds:

Caution
There is a performance hit taken by enabling the slow query log feature. This is due to the additional routines needed to analyze each query as well as the I/O needed to write the necessary queries to the log file. Because of this, it is considered best practice on production systems to disable the slow query log. The slow query log should only remain enabled for a specific duration when actively looking for troublesome queries that may be impacting the application or website.
# Time: 180717 0:23:28
# User@Host: root[root] @ localhost [] # Thread_id: 32 Schema: employees QC_hit: No
# Query_time: 627.163085 Lock_time: 0.000021 Rows_sent: 0 Rows_examined: 0
# Rows_affected: 0
use employees;
SET timestamp=1531801408;
call While_Loop2();

Optionally, you can use the mysqldumpslow command line tool, which parses the slow query log file and groups like queries together except values of number and string data:
~ $ mysqldumpslow -a /var/lib/mysql/slowquery.log
Reading mysql slow query log from /var/lib/mysql/slowquery.log
Count: 2 Time=316.67s (633s) Lock=0.00s (0s) Rows_sent=0.5 (1), Rows_examined=0.0 (0), Rows_affected=0.0 (0), root[root]@localhost
call While_Loop2()(For usage information visit MySQL documentation here: mysqldumpslow – Summarize Slow Query Log Files)

So concludes the first part of our Database Optimization series and gives us a solid basis to refer back to for benchmark purposes. Though database issues can be complicated, our series will break down these concepts to provide means to optimize your database through database conversion, table conversion, and indexing.

 

MySQL Performance: MyISAM vs InnoDB

Posted on by J. Potter
Category: Series | Tags: , , , , , , ,

 

A major factor in database performance is the storage engine used by the database, and more specifically, its tables. Different storage engines provide better performance in one situation over another. For general use, there are two contenders to be considered. These are MyISAM, which is the default MySQL storage engine, or InnoDB, which is an alternative engine built-in to MySQL intended for high-performance databases. Before we can understand the difference between the two storage engines, we need to understand the term “locking.”

To protect the integrity of the data stored within databases, MySQL employs locking. Locking, simply put, means protecting data from being accessed. When a lock is applied, the data cannot be modified except by the query that initiated the lock. Locking is a necessary component to ensure the accuracy of the stored information.  Each storage engine has a different method of locking used. Depending on your data and query practices, one engine can outperform another. In this series, we will look at the two most common types of locking employed by our two storage engines.

 

Table locking:  The technique of locking an entire table when one or more cells within the table need to be updated or deleted. Table locking is the default method employed by the default storage engine, MyISAM.

Example: MyISAM Table LockingColumn AColumn BColumn C
Query 1 UPDATERow 1Writingdatadata
Query 2 SELECT (Wait)Row 2datadatadata
Query 3 UPDATE (Wait)Row 3datadatadata
Query 4 SELECT (Wait)Row 4datadatadata
Query 5 SELECT (Wait)Row 5datadatadata
The example illustrates how a single write operation locks the entire table causing other queries to wait for the UPDATE query finish.

 

Row-level locking: The act of locking an effective range of rows in a table while one or more cells within the range are modified or deleted. Row-level locking is the method used by the InnoDB storage engine and is intended for high-performance databases.

Example: InnoDB Row-Level LockingColumn AColumn AColumn A
Query 1 UPDATERow 1Writingdatadata
Query 2 SELECTRow 2Readingdatadata
Query 3 UPDATERow 3dataWritingdata
Query 4 SELECTRow 4ReadingReadingReading
Query 5 SELECTRow 5ReadingdataReading
The example shows how using row-level locking allows for multiple queries to run on individual rows by locking only the rows being updated instead of the entire table.

 

By comparing the two storage engines, we get to the crux of the argument between using InnoDB over MyISAM. An application or website that has a frequently used table works exceptionally well using the InnoDB storage engine by resolving table-locking bottlenecks. However, the question of using one over the other is a subjective as neither of them is perfect in all situations. There are strengths and limitations to both storage engines. Intimate knowledge of the database structure and query practices is critical for selecting the best storage engine for your tables.

MyISAM will out-perform InnoDB on large tables that require vastly more read activity versus write activity. MyISAM’s readabilities outshine InnoDB because locking the entire table is quicker than figuring out which rows are locked in the table. The more information in the table, the more time it takes InnoDB to figure out which ones are not accessible. If your application relies on huge tables that do not change data frequently, then MyISAM will out-perform InnoDB.  Conversely, InnoDB outperforms MyISAM when data within the table changes frequently. Table changes write data more than reading data per second. In these situations, InnoDB can keep up with large amounts of requests easier than locking the entire table for each one.

 

Should I use InnoDB with WordPress, Magento or Joomla Sites?

The short answer here is yes, in most cases. Liquid Web’s Most Helpful Humans in Hosting Support Teams have encountered several table-locking bottlenecks when clients are using some of the standard web applications of today. Most users of popular third-party applications like WordPress, Magento, and Joomla have limited knowledge of the underlying database components or code involved to make an informed decision on storage engines. Most table-locking bottlenecks from these content management systems (CMS) are generally resolved by changing all the tables for the site over to  InnoDB instead of the default MyISAM.  If you are hosting many of these types of CMS on your server, it would be beneficial to change the default storage engine in MySQL to use InnoDB for all new tables so that any new table installations start off with InnoDB.

 

Set your default storage engine to InnoDB by adding default_storage_engine=InnoDB to the [mysqld] section of the system config file located at:  /etc/my.cnf . Restarting the MySQL service is necessary for the server to detect changes to the file.

~ $ cat /etc/my.cnf
[mysqld]
log-error=/var/lib/mysql/mysql.err
innodb_file_per_table=1
default-storage-engine=innodb
innodb_buffer_pool_size=128M

 

Unfortunately, MySQL does not inherently have an option to convert tables, leaving each table to be changed individually. Liquid Web’s support team has put together an easy to follow maintenance plan for this process. The script, which you can run on the necessary server via shell access (SSH) will convert all tables between storage engines.

Note
Plan accordingly when performing batch operations of this nature just in case downtime occurs. Best practice is to backup all your MySQL Databases before implementing a change of this magnitude, doing so provides an easy recovery point to prevent any data loss.

Step 1: Prep

Plan to start at a time of day where downtime would have minimal consequences. This process itself does not require any downtime, however, downtime may be necessary to recover from unforeseen circumstances.  

 

Step 2: Backup All Databases To A File

The command below creates a single file backup of all databases named all-databases-backup.sqld and can be deleted once the conversion has succeeded and there are no apparent problems.
mysqldump --all-databases > all-databases-backup.sql

 

Step 3: Record Existing Table Engines To A File

Run the following script to record the existing table engines to a file named table-engine-backup.sql. You can then “import” or “run” this file later to convert back to their original engines if necessary.

mysql -Bse 'SELECT CONCAT("ALTER TABLE ",table_schema,".",table_name," ENGINE=",Engine,";") FROM information_schema.tables WHERE table_schema NOT IN("mysql","information_schema","performance_schema");' | tee table-engine-backup.sql

If you need to revert the table engines back for any reason, run:
mysql < table-engine-backup.sql

 

Step 4a: Convert MyISAM Tables To InnoDB

The below command will proceed even if a table fails and lets you know which tables failed to convert. The output is saved to the file named convert-to-innodb.log for later review.
mysql -Bse 'SELECT CONCAT("ALTER TABLE ",table_schema,".",table_name," ENGINE=InnoDB;") FROM information_schema.tables WHERE table_schema NOT IN ("mysql","information_schema","performance_schema") AND Engine = "MyISAM";' | while read -r i; do echo $i; mysql -e "$i"; done | tee convert-to-innodb.log

 

Step 4b: Convert All InnoDB Tables To MyISAM

This command will proceed even if a table fails and lets you know which tables failed to convert. The output is also saved to the file named convert-to-myisam.log for later review.

mysql -Bse 'SELECT CONCAT("ALTER TABLE ",table_schema,".",table_name," ENGINE=MyISAM;") FROM information_schema.tables WHERE table_schema NOT IN ("mysql","information_schema","performance_schema") AND Engine = "InnoDB";' | while read -r i; do echo $i; mysql -e "$i"; done | tee convert-to-myisam.log

 

The following commands illustrate how converting a single table is accomplished.

Note
Replace database_name with the proper database name and table_name with the correct table name. Make sure you have a valid backup of the table in question before proceeding. 

Backup A Single Table To A File
mysqldump database_name table_name > backup-table_name.sql

 

Convert A Single Table To InnoDB

mysql -Bse ‘ALTER TABLE database_name.table_name ENGINE=InnoDB;’

 

Convert A Single Table To MyISAM:

mysql -Bse ‘ALTER TABLE database_name.table_name ENGINE=MyISAM;’

 

Check out our other articles in this series, MySQL Performance: Identifying Long Queries, to pinpoint slow queries within your database.  Stay tuned for our next article where we will cover caching and optimization.

MySQL Performance: How To Leverage MySQL Database Indexing

Posted on by J. Potter
Category: Series | Tags: , , , , , , , , , , , ,

A Mysql Indexing Logo

Throughout this tutorial, we will cover some of the fundamentals of indexing. As part of the MySQL series, we will introduce capabilities of MySQL indexing and the role it plays in optimizing database performance. Liquid Web recommends consulting with a DBA before making any changes to your production level application.

What is Indexing?

Indexing is a powerful structure in MySQL which can be leveraged to get the fastest response times from common queries. MySQL queries achieve efficiency by generating a smaller table, called an index, from a specified column or set of columns. These columns, called a key, can be used to enforce uniqueness. Below is a simple visualization of an example index using two columns as a key.

+------+----------+----------+
| ROW | COLUMN_1 | COLUMN_2 |
+------+----------+----------+
| 1 | data1 | data2 |
+------+----------+----------+
| 2 | data1 | data1 |
+------+----------+----------+
| 3 | data1 | data1 |
+------+----------+----------+
| 4 | data1 | data1 |
+------+----------+----------+
| 5 | data1 | data1 |
+------+----------+----------+

Queries utilize indexes to identify and retrieve the targeted data, even if they are a combination of keys. Without an index, running that same query results in an inspection of every row for the needed data. Indexing produces a shortcut, with much faster query times on expansive tables. A textbooks analogy may provide another common way to visualize how indexes function.
This analogy compares MySQL indexing to indexing in the back of a book.

When to Enable Indexing?

Indexing is only advantageous for huge tables with regularly accessed information. For instance, to continue with our textbook analogy, it makes little sense to index a children’s storybook with only a dozen pages. It’s more efficient to simply read the book to find each occurrence of the word “turtle” than it would be to set up and maintain indexes, query for those indexes, and then review each page provided. In the computing world, those extra tasks surrounding indexing represent wasted resources which would be better purposed by not indexing.

Without indexes, when tables grow to enormous proportions, response times suffer from queries targeting those obtuse tables. Inefficient queries manifest into latency within application or website performance. We commonly identify this latency by using the MySQL slow query log feature. You can find more details about using the slow query log feature in the first article in this series: MySQL Performance: Identifying Long Queries.
Once a colossal table hits its tipping point, it reaches the potential for downtime for applications and websites. Conducting routine evaluations for growing database establishes optimal database performance and sidesteps long queries’ inherent interruptions.

MySQL Indexing Pros vs. Cons

There are benefits and downsides to using MySQL indexing, and we’ll discuss the significant pros and cons for your consideration. These aspects will guide you to decide whether indexing is an appropriate choice for your situation.

quick data transmissions and ideal for OLAP.

What Information Does One Index?

Selecting what to index is probably the most challenging part to indexing your databases. Determining what is important enough to index and what is benign enough to not index. Generally speaking, indexing works best on those columns that are the subject of the WHERE clauses in your commonly executed queries. Consider the following simplified table:

ID, TITLE, LAST_NAME, FIRST_NAME, MAIDEN_NAME, DOB, GENDER, AGE, DESCRIPTION, HISTORY, ETC...

If your queries rely on testing the WHERE clause using LAST_NAME and FIRST_NAME then indexing by these two columns would significantly increase query response times. Alternately, if your queries rely on a simple ID lookup, indexing by ID would be the better choice.

These examples are merely a rudimentary example, and there are several types of indexing structures built-in to MySQL. The following MySQL page discusses these types of indexes in greater detail, and a recommended read for anyone considering indexing: How MySQL Uses Indexes

What is a Unique Index?

Another point for consideration when evaluating which columns to serve as the key in your index is whether to use the UNIQUE constraint. Setting the UNIQUE constraint will enforce uniqueness based on the configured indexing key. As with any key, this can be a single column or a concatenation of multiple columns. The function of this constraint ensures that there are no duplicate entries in the table based on the configured key.

UNIQUE constraints increase write speeds, a taxation of implementation.

What is a Primary Key Index?

As commonly invoked as the UNIQUE constraint the PRIMARY KEY is used to optimize indexes. This constraint ensures that the designated PRIMARY KEY cannot be of a null value. As a result, a performance boost occurs when running on an InnoDB storage engine for the table in question. This boost is due to how InnoDB physically stores data, placing null valued rows in the key out of contiguous sequence with rows that have values. Enabling this constraint ensures the rows of the table are kept in contiguous order for quicker responses.

Primary Key Index is absolutely necessary for large tables.

Managing Indexes

Now we will cover some of the basics of manipulating indexes using MySQL syntax. In examples, we will include the creation, deletion, and listing of indexes.Keywords for Managing Indexes: dbName, tableName, indexName Keep in mind, these examples have placeholder entries for the specific keywords. These keywords are self-explanatory by nature for easy reading, and below is an outline of them.

Instead of tableName you can use dbName.tableName.

Listing/Showing Indexes

Tables can have multiple indexes. Managing indexes will inevitably require being able to list the existing indexes on a table. The syntax for viewing an index is below.

SHOW INDEX FROM tableName;

SHOW INDEX FROM tableName; shows all indexes.

Indexing are present on 3 different columns.

Creating Indexes

Index creation has a simple syntax. The difficulty is in determining what columns need indexing and whether enforcing uniqueness is necessary. Below we will illustrate how to create indexes with and without a PRIMARY KEY and UNIQUE constraints.

As previously mentioned, tables can have multiple indexes. Multiple indexing is useful for creating indexes attuned to the queries required by your application or website. The default settings allow for up to 16 indexes per table, increase this number but is generally more than is necessary. Indexes can be created during a table’s creation or added on to the table as additional indexes later on. We will go over both methods below.

Creating too many indexes can add latency, but if you must then increase buffers in MySQL config.

Example: Create a Table with a Standard Index

CREATE TABLE tableName (
ID int,
LName varchar(255),
FName varchar(255),
DOB varchar(255),
LOC varchar(255),
INDEX ( ID )
);You can create an index for several columns, using ID as the index.

Example: Create a Table with Unique Index & Primary Key

CREATE TABLE tableName (
ID int,
LName varchar(255),
FName varchar(255),
DOB varchar(255),
LOC varchar(255),
PRIMARY KEY (ID),
UNIQUE INDEX ( ID )
);You can create an Primary Key and UNIQUE constraint over several columns.

Example: Add an Index to Existing Table

CREATE INDEX indexName ON tableName (ID, LName, FName, LOC);CREATE INDEX statement creates an index and names it.

Example: Add an Index to Existing Table with Primary Key

CREATE UNIQUE INDEX indexName ON tableName (ID, LName, FName, LOC);the CREATE UNIQUE command can add an index to a table ensuring no duplicate data.

Deleting Indexes

While managing indexes, you may find it necessary to remove some. Deleting indexes is also a very simple process, see the example below:

DROP INDEX indexName ON tableName;The DROP INDEX command lets us drop indexes on particular column.

There are many ways to optimize your database for true efficiency. If you would like to learn more or convert the search engines types available in MySQL read through our MyISAM vs. InnoDB tutorial.  Or if you are need of high functioning databases check out our MySQL product page to view different options.

MySQL Performance: MySQL vs. MariaDB

Posted on by J. Potter | Updated:
Category: Series | Tags: , , ,

MariaDB and MySQL logos.

We continue our series on MySQL Optimization by focusing on the differences and similarities between MariaDB and MySQL. MariaDB is a popular alternative to using traditional MySQL for database hosting. The free market of hosting allows additional actors to compete with the long-standing database solution, MySQL. MariaDB is the most prominent alternative to MySQL and is a favorite among industry giants such as Google, Craigslist, Wikipedia, Arch Linux, RedHat, CentOS, Fedora, and cPanel. In a direct performance comparison, MariaDB leaps to the head of the pack through performance optimizations, easy of conversion and compatibility.

Why Switch to MariaDB?

MariaDB is mostly a clone of MySQL, but it also provides several improvements over running the standard MySQL instance. MariaDB aims for a drop-in replacement to MySQL, which makes the switch painless and straightforward. Combine the simplicity of switching with a long list of improvements, MariaDB brings both performance and cutting-edge features to the table. Below are some of its selling points over standard MySQL.

More Storage Engines Options: There is 12 new storage engine built into MariaDB. Among these are CONNECT, Spider, and SphinxSE. Visit their Storage Engines page for a complete list of these engines, how they function, and ways to leverage them to optimize your database.

Speed improvements: MariaDB sports many new speed improvements compared directly with standard MySQL. This improved performance makes MariaDB stand apart from the baseline performance of traditional MySQL servers. Like MySQL, MariaDB has dozens of features for speed optimization including disk access, JOIN and EXPLAIN improvements, subquery, derived tables/views, execution control, and optimizer control.

Faster Indexes/Cache: When using the MEMORY storage engine, MariaDB can complete INSERT statements up to 24% faster than traditional MySQL servers, along with CHECKSUM TABLE and MyISAM Segment Key Cache being 4x faster.

Speedier and Larger Connection Pool: MariaDB benefits from an improved pool of threads that run faster and support up to 200,000+ connections where standard MySQL falls short.

Improved Replication: MariaDB sports faster and safer replication with updates being up to 2x faster than with traditional MySQL Replication setups. Now possible, parallel replication allows the existence of Active/Active or Master/Master configurations. MariaDB replication is backward compatible with MySQL servers, so migrating your cluster to MariaDB is possible by utilizing one node at a time.

New Extensions/Features: There are several new extension and features, to name a few, the WITH, JSON and KILL statements. DECIMAL sees an increased from 30 to 38 decimals while KILL ALL queries for a specified user.

List of Features: Available MariaDB’s website is a comprehensive list of improvements and features, located here: MariaDB versus MySQL-Features.

 

What is the Downside to Using MariaDB?

The MariaDB project is entirely open-source and free, unlike MySQL which uses dual licensing to keep its Enterprise edition specific features proprietary. The MariaDB developers actively update and enhance with cutting-edge features that standard MySQL does not carry.

Missing Features: MySQL uses some proprietary code in its Enterprise Edition. MariaDB does not have access to this propriety content and is a closed source, meaning the features are only available to MySQL Enterprise users.

Mitigation: MariaDB has addressed this concern through allowing viable open-source alternative plugins for MariaDB, providing the same functionality that the MySQL Enterprise Edition offers. This allows the vast majority of standard MySQL and MySQL Enterprise Edition users the option to switch to MariaDB, taking advantage of its robust performance enhancing features.

Delayed MySQL Compatibility: MariaDB originally forked from MySQL 5.5, so this is the base starting point for the MariaDB source code. Meaning that newer features and bug fixes developed for standard MySQL after version 5.5 are not part of the existing MariaDB source code.

Mitigation: MariaDB conducts monthly merges of the standard MySQL source code to ensure both compatibility and feature/bug-fix adoption. This kind of regular code merging, allows MariaDB to maintain its allure as a drop-in replacement for practically any existing versions of standard MySQL. However, there will always be a delay causing MariaDB to lag behind MySQL’s newer features and bug patches.

MySQL Performance: Converting MySQL to MariaDB

Posted on by J. Potter | Updated:
Category: Series | Tags: , , , , , , ,

As we explored in our previous article of our MySQL Perfomance Series: MySQL vs. MariaDB there are very few downsides to using MariaDB over standard MySQL. Our high-availbility MariaDBs have proven itself to be a worthy successor with easily migitated drawbacks.  As the last article in our series we will focus on upgrading to various MySQL and MariaDB version on the following servers:

CentOS 6/7

Ubuntu 14.04/16.04

Choosing a MariaDB Upgrade Plan

Selecting the right upgrade plan requires determining which version of MySQL is running on the intended system. A universal method of determining what version of MySQL the server is currently running is to query the server itself to report the version. This works the same despite the Linux distribution running on the server:

mysql -h localhost -e 'SHOW VARIABLES LIKE "version"\G'

Example Output:

~ $ mysql -h localhost -p -e 'SHOW VARIABLES LIKE "version"\G'
*************************** 1. row ***************************
Variable_name: version
Value: 5.5.61-MariaDB Be sure not you are connecting to a local server when performing this check.

Once you’ve identified your MySQL version, use the key below to locate the correct upgrade procedure for your particular server. Some versions of MySQL require upgrading to MariaDB 5.5 before upgrading to MariaDB 10.x versions.

Upgrading from MySQL  to MariaDB

The upgrade process is similar between most server types. There are differences with the specific commands that are executed, but the overall procedure follows this General Upgrade Procedure:

  1. Schedule accurate downtime.
  2. Ensure adequate backups.
  3. Remove the existing MySQL binaries/packages.
  4. Install the correct MariaDB repository.
  5. Clear repository caches to expunge old package data.
  6. Install MariaDB packages via the system’s package manager.
  7. Start MariaDB by starting the MySQL service.
  8. Run MySQL upgrade script.
  9. Confirm MySQL databases are accessible and data is correct

We’ve included specific procedures below for various Liquid Web systems. Before choosing your applicable upgrade procedure, let us review the first two steps in the above General Upgrade Procedure. These steps are generally universal and are critical to the success of any maintenance plan.

Schedule Accurate Downtime

Scheduling proper maintenance windows to perform changes affecting production environments can be tricky. The maintenance event window must include enough time to perform all necessary tasks in the maintenance plan, plus any troubleshooting and extra time to complete the Reversion Plan if needed.

When calculating MySQL maintenance windows, double your estimated calculation plus 20 mins.

Ensure Adequate Backups

There is more to a maintenance backup plan than just backing up files and databases. It’s also necessary to form a Reversion Plan, which outlines the process to restore the environment to its original state before the start of the maintenance.
Maintenance events can sometimes lead to unforeseen issues with the alternative of reverting to backups. Having both a valid backup plan and a valid reversion plan to restore services is a critical component of successful maintenance. Below are outlines of both a Sample Backup Plan and a Sample Reversion Plan which can be used in conjunction with this article’s upgrade procedure outlines.

Sample Backup Plan

Create a backup of all databases.

mysqldump --all-databases –add-drop-database > all-databases-backup.sqlThis command has no visible output unless errors occur. The above command creates a single file backup of all databases used for easy restoration when using the –add-drop-database flag. This .sql file can re-imported into MySQL for deletion and re-creations of all databases. The file created is named all-databases-backup.sql and will be needed later in the Sample Reversion Plan. Be sure you have enough space when making a MySQL backup of all your databases. Table locking occurs when performing a MySQL backup.

Create a backup of MySQL’s configuration file.

cp -p /etc/my.cnf{,.bak}This command has no visible output unless errors occur. The above command will create an exact copy of /etc/my.cnf named /etc/my.cnf.bak which can be used to restore the configuration if needed.

Sample Reversion Plan
Step 1: Restore all databases into MySQL mysql < all-databases-backup.sqlThis command has no visible output unless errors occur.   Step 2:Preserve existing config by renaming /etc/my.cnf to /etc/my.cnf.bak mv -p /etc/my.cnf{,.bad}This command has no visible output unless errors occur.   Step 3: Copy the /etc/my.cnf.bak file to /etc/my.cnf cp -p /etc/my.cnf{.bak,}This command has no visible output unless errors occur.   Step 4: Restart MySQL Service service mysqld restart Example Output:~ $ service mysqld restart
Stopping mysqld: [ OK ] Starting mysqld: [ OK ]Mysqld has switched to mysql.

MySQL to MariaDB on CentOS 6/7 with cPanel

All Liquid Web cPanel server images include MariaDB 5.5 already installed. This includes both CentOS 6 and CentOS 7 server images. There is no need to upgrade unless the MariaDB 10.x series is required. For a manual upgrade, procedures as provided by MariaDB here: Upgrading from MariaDB 5.5 to MariaDB 10.0, otherwise, cPanel provides an easy point-&-click interface which does all the heavy lifting for you. Follow one of the procedures below in either TexT Only form or Graphical form.

With upgrades it best to schedule off of peak functioning hours.

cPanel MariaDB Upgrade Instructions:

Step A) Confirm backups are present before proceeding at the scheduled time.

Step B) Login to WHM and load the MySQL/MariaDB Upgrades page:

WHM allows you to upgrade your MySQL versions with just a few clicks.

① Use the quick search box on the left and type in: mysql upgrade

② Locate and Click the MySQL/MariaDB Upgrades link.

③ Selected your desired version of MariaDB.        

④ Click the Next button.

Step C) Wait for the “Upgrade Warnings” page to finish loading.

WHM will warn you of any potential consequences before upgrading MySQL.

① Read & acknowledge each warning message by enabling each checkbox.

② Click the Continue button.

Step D) Wait for the “Upgrade Type” page to finish loading.

WHM prompts for the upgrade type for MySQL.

① Select Unattended Upgrade for a seamless upgrade experience.

② Click the Continue button.

Step E) Wait for the Upgrade Process to complete.

WHM browser can be closed without interrupting MySQL update.MySQL to MariaDB on CentOS 7 with Plesk Onyx 17

All Liquid Web CentOS 7 server images include MariaDB 5.5 already installed, including our CentOS 7 Plesk Onyx 17 servers. There is no need to upgrade unless the MariaDB 10.x series is required. In these cases, follow the standard MariaDB Plesk Upgrade Procedures here: How to upgrade MySQL 5.5 to 5.6/5.7 or MariaDB 5.5 to 10.0/10.1/10.2 on Linux

 

MySQL 5.1-5.5 to MariaDB 5.5 on CentOS 6

Due to compatibility limitation, MySQL 5.1, 5.2, 5.3 and 5.5.x must be upgraded to MariaDB 5.5 and cannot be upgraded to MariaDB 10.0 directly. This upgrade plan will walk through getting any one of these deprecated MySQL versions upgraded to MariaDB 5.5.  Once the upgrade to MariaDB 5.5 is complete, follow the How to upgrade MariaDB 5.5 to MariaDB 10.0 on CentOS 6 instructions to continue the upgrade process to MariaDB 10.

Step 1: Confirm backups are present before proceeding at the scheduled time.

Step 2: Stop the MySQL service.

service mysqld stop

Example Output:
~ $ service mysqld restart
Stopping mysqld: [ OK ]

Mysqld has switched to mysql.Step 3: Install the MariaDB 5.5 repository for CentOS 6

cat < /etc/yum.repos.d/MariaDB.repo
[mariadb] name = MariaDB
baseurl = http://yum.mariadb.org/5.5/centos6-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1
EOFThis command has no visible output unless errors occur.

Step 4: Clean the yum repository cache

yum clean allExample Output:

~ $ yum clean all
Loaded plugins: fastestmirror
Cleaning repos: base extras mariadb updates
Cleaning up Everything
Cleaning up list of fastest mirrors

Step 5: Remove MySQL packages

yum remove mysql-server mysqlExample Output:

Running Transaction Test
Transaction Test Succeeded
Running Transaction
Erasing : mysql-server-5.1.73-8.el6_8.x86_64 1/1
warning: /var/log/mysqld.log saved as /var/log/mysqld.log.rpmsave
Verifying : mysql-server-5.1.73-8.el6_8.x86_64 1/1
Removed:
mysql-server.x86_64 0:5.1.73-8.el6_8
Complete!Truncated for brevity.

Step 6: Install the MariaDB-server and MariaDB-client packages via yum.

yum install MariaDB-server MariaDB-client -y

Example Output:Installed:
MariaDB-client.x86_64 0:10.1.35-1.el6 MariaDB-compat.x86_64 0:10.1.35-1.el6 MariaDB-server.x86_64 0:10.1.35-1.el6
Dependency Installed:
MariaDB-common.x86_64 0:10.1.35-1.el6 boost-program-options.x86_64 0:1.41.0-28.el6
galera.x86_64 0:25.3.23-1.rhel6.el6 jemalloc.x86_64 0:3.6.0-1.el6
Replaced:
mysql-libs.x86_64 0:5.1.73-8.el6_8
Complete!Truncated for brevity.

Step 7: Restart the MySQL service

service mysql startExample Output:

~ $ service mysql start
Starting MariaDB.180808 18:21:13 mysqld_safe Logging to '/var/lib/mysql/cent6.hostname.err'.
180808 18:21:13 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
SUCCESS!Mysqld has switched to mysql.Step 8: Run MySQL upgrade tool

mysql_upgradeExample Output:

~ $ mysql_upgrade
MySQL upgrade detected
Phase 1/4: Fixing views from mysql
mysql
mysql.columns_priv OK
mysql.db OK
mysql.event OK
mysql.func OK
mysql.time_zone_leap_second OK
mysql.time_zone_name OK
mysql.time_zone_transition OK
mysql.time_zone_transition_type OK
mysql.user OK
Phase 4/4: Running 'mysql_fix_privilege_tables'
OKTruncated for brevity.

Step 9: Confirm MariaDB server is running as expected

mysql -e 'SHOW VARIABLES LIKE "version"\G'Example Output:

~ $ mysql -e 'SHOW VARIABLES LIKE "version"\G'
*************************** 1. row ***************************
Variable_name: version
Value: 5.5.61-MariaDB

Step 10: The upgrade is complete, check that your databases exist and are working.

[ Optional ] follow the How to upgrade MariaDB 5.5 to MariaDB 10.0 on CentOS 6 instructions.

MariaDB 5.5 to MariaDB 10.0 on CentOS 6

Step 1:  Confirm backups are present before proceeding at the scheduled time.

Step 2: Remove all MariaDB packages.

yum remove MariaDB-*Example Output:
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Erasing : MariaDB-server-5.5.61-1.el6.x86_64 1/2
Erasing : MariaDB-client-5.5.61-1.el6.x86_64 2/2
Verifying : MariaDB-server-5.5.61-1.el6.x86_64 1/2
Verifying : MariaDB-client-5.5.61-1.el6.x86_64 2/2
Removed:
MariaDB-client.x86_64 0:5.5.61-1.el6 MariaDB-server.x86_64 0:5.5.61-1.el6
Complete!Truncated for brevity.

Step 3: Remove existing MariaDB repository.

rm -f /etc/yum.repos.d/MariaDB*.repoThis command has no visible output unless errors occur.

Step 4: Create MariaDB 10.O Yum repository file.

cat < /etc/yum.repos.d/MariaDB.repo
[mariadb] name = MariaDB
baseurl = http://yum.mariadb.org/10.0/centos6-amd64
gpgkey=https://yum.mariadb.org/RPM-GPG-KEY-MariaDB
gpgcheck=1
EOF This command has no visible output unless errors occur.

Step 5: Clean the Yum cache.

yum clean all

Example Output:

~ $ yum clean all
Loaded plugins: fastestmirror
Cleaning repos: base extras mariadb updates
Cleaning up Everything
Cleaning up list of fastest mirrors

Step 6: Install MariaDB-server and MariaDB-client package via Yum.

yum install MariaDB-server MariaDB-clientExample Output:

Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : MariaDB-client-10.0.36-1.el6.x86_64 1/2
Installing : MariaDB-server-10.0.36-1.el6.x86_64 2/2
Verifying : MariaDB-server-10.0.36-1.el6.x86_64 1/2
Verifying : MariaDB-client-10.0.36-1.el6.x86_64 2/2
Installed:
MariaDB-client.x86_64 0:10.0.36-1.el6 MariaDB-server.x86_64 0:10.0.36-1.el6
Complete!
Truncated for brevity.

Step 7: Start the MySQL Service.

service mysql start

Step 8: Run the MySQL Upgrade script.

mysql_upgrade

Step 9: The upgrade is complete, check that your databases exist and are working.

 

MySQL 5.1-5.5 to MariaDB 5.5 on Ubuntu 14.04

Step 1:  Confirm backups are present before proceeding at the scheduled time.

Step 2: Install the MariaDB 5.5 repository with this one-liner it’ll install the necessary required tools (if missing), the Ubuntu 14.04 GPG key and the MariaDB 5.5 repository while updating the apt package caches.

sudo apt-get install software-properties-common -y
sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
sudo add-apt-repository 'deb [arch=amd64,i386,ppc64el] http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu trusty main'
sudo apt-get update
Example Output:
~ $ sudo apt-get install software-properties-common -y > /dev/null
~ $ sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
Executing: gpg --ignore-time-conflict --no-options --no-default-keyring --homedir /tmp/tmp.PtpHIXMNvY --no-auto-check-trustdb --trust-model always --keyring /etc/apt/trusted.gpg --primary-keyring /etc/apt/trusted.gpg --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xcbcb082a1bb943db
gpg: requesting key 1BB943DB from hkp server keyserver.ubuntu.com
gpg: key 1BB943DB: public key "MariaDB Package Signing Key <package-signing-key@mariadb.org>" imported
gpg: Total number processed: 1
gpg: imported: 1
~ $ sudo add-apt-repository 'deb [arch=amd64,i386,ppc64el] http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu trusty main'
~ $ sudo apt-get update > /dev/nullTruncated for brevity.

Step 3: Stop mysql service.

sudo service mysql stop
Example Output:
~ $ sudo service mysql stop
mysql stop/waiting

Step 4: Rename MySQL config file /etc/mysql/my.cnf to /etc/mysql/my.cnf.bak. This step is necessary to ensure all incompatible directives/variables have been removed from the configuration to prevent problems with the install.

sudo mv /etc/mysql/my.cnf{,.bak}

Check out incompatible directives.Step 5: Install the mariadb-server package. This will simultaneously remove the existing MySQL binaries and then install the new MariaDB binaries.
sudo apt-get install mariadb-server -y

Example Output:
Example Output: ~ $ sudo apt-get install mariadb-server -y
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-3.13.0-153 linux-headers-3.13.0-153-generic
linux-headers-3.13.0-24 linux-headers-3.13.0-24-generic
linux-headers-3.13.0-91 linux-headers-3.13.0-91-generic
linux-image-3.13.0-153-generic linux-image-3.13.0-24-generic
linux-image-3.13.0-91-generic
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
libmariadbclient18 libmysqlclient18 mariadb-client-5.5
mariadb-client-core-5.5 mariadb-common mariadb-server-5.5
mariadb-server-core-5.5
Suggested packages:
tinyca mailx mariadb-test
The following packages will be REMOVED:
mysql-client-5.5 mysql-client-core-5.5 mysql-server mysql-server-5.5
mysql-server-core-5.5
The following NEW packages will be installed:
libmariadbclient18 mariadb-client-5.5 mariadb-client-core-5.5 mariadb-common
mariadb-server mariadb-server-5.5 mariadb-server-core-5.5
The following packages will be upgraded:
libmysqlclient18
1 upgraded, 7 newly installed, 5 to remove and 1 not upgraded.
Need to get 10.4 MB of archives.
After this operation, 22.1 MB of additional disk space will be used.
Get:1 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-common all 5.5.61+maria-1~trusty [3,180 B] Get:2 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main libmysqlclient18 amd64 5.5.61+maria-1~trusty [2,862 B] Get:3 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main libmariadbclient18 amd64 5.5.61+maria-1~trusty [521 kB] Get:4 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-client-core-5.5 amd64 5.5.61+maria-1~trusty [622 kB] Get:5 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-client-5.5 amd64 5.5.61+maria-1~trusty [961 kB] Get:6 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-server-core-5.5 amd64 5.5.61+maria-1~trusty [3,831 kB] Get:7 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-server-5.5 amd64 5.5.61+maria-1~trusty [4,413 kB] Get:8 http://ftp.osuosl.org/pub/mariadb/repo/5.5/ubuntu/ trusty/main mariadb-server all 5.5.61+maria-1~trusty [2,896 B] Fetched 10.4 MB in 1s (7,992 kB/s)
Preconfiguring packages ...
(Reading database ... 165598 files and directories currently installed.)
Removing mysql-server (5.5.61-0ubuntu0.14.04.1) ...
Removing mysql-server-5.5 (5.5.61-0ubuntu0.14.04.1) ...
mysql stop/waiting
Removing mysql-client-5.5 (5.5.61-0ubuntu0.14.04.1) ...
Removing mysql-client-core-5.5 (5.5.61-0ubuntu0.14.04.1) ...
Removing mysql-server-core-5.5 (5.5.61-0ubuntu0.14.04.1) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Selecting previously unselected package mariadb-common.
(Reading database ... 165377 files and directories currently installed.)
Preparing to unpack .../mariadb-common_5.5.61+maria-1~trusty_all.deb ...
Unpacking mariadb-common (5.5.61+maria-1~trusty) ...
Preparing to unpack .../libmysqlclient18_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking libmysqlclient18 (5.5.61+maria-1~trusty) over (5.5.61-0ubuntu0.14.04.1) ...
Selecting previously unselected package libmariadbclient18.
Preparing to unpack .../libmariadbclient18_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking libmariadbclient18 (5.5.61+maria-1~trusty) ...
Selecting previously unselected package mariadb-client-core-5.5.
Preparing to unpack .../mariadb-client-core-5.5_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking mariadb-client-core-5.5 (5.5.61+maria-1~trusty) ...
Selecting previously unselected package mariadb-client-5.5.
Preparing to unpack .../mariadb-client-5.5_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking mariadb-client-5.5 (5.5.61+maria-1~trusty) ...
Selecting previously unselected package mariadb-server-core-5.5.
Preparing to unpack .../mariadb-server-core-5.5_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking mariadb-server-core-5.5 (5.5.61+maria-1~trusty) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Setting up mariadb-common (5.5.61+maria-1~trusty) ...
Selecting previously unselected package mariadb-server-5.5.
(Reading database ... 165514 files and directories currently installed.)
Preparing to unpack .../mariadb-server-5.5_5.5.61+maria-1~trusty_amd64.deb ...
Unpacking mariadb-server-5.5 (5.5.61+maria-1~trusty) ...
Selecting previously unselected package mariadb-server.
Preparing to unpack .../mariadb-server_5.5.61+maria-1~trusty_all.deb ...
Unpacking mariadb-server (5.5.61+maria-1~trusty) ...
Processing triggers for man-db (2.6.7.1-1ubuntu1) ...
Processing triggers for ureadahead (0.100.0-16) ...
Setting up libmysqlclient18 (5.5.61+maria-1~trusty) ...
Setting up libmariadbclient18 (5.5.61+maria-1~trusty) ...
Setting up mariadb-client-core-5.5 (5.5.61+maria-1~trusty) ...
Setting up mariadb-client-5.5 (5.5.61+maria-1~trusty) ...
Setting up mariadb-server-core-5.5 (5.5.61+maria-1~trusty) ...
Setting up mariadb-server-5.5 (5.5.61+maria-1~trusty) ...
Installing new version of config file /etc/apparmor.d/usr.sbin.mysqld ...
Installing new version of config file /etc/init.d/mysql ...
Installing new version of config file /etc/logrotate.d/mysql-server ...
Installing new version of config file /etc/mysql/debian-start ...
mysql start/running, process 7255
Processing triggers for ureadahead (0.100.0-16) ...
Setting up mariadb-server (5.5.61+maria-1~trusty) ...
Processing triggers for libc-bin (2.19-0ubuntu6.14) ...

Step 6: During the installation an on-screen dialog will appear prompting to change the MySQL root password twice. Follow the instructions to either change the password or skip the change by providing a blank password.

Changing the MySQL root password is advised when upgrading.
Step 7: When completed successfully, the mysql service should automatically start and the mysql_upgrade script is completed automatically during the install process.

A) Check that the mysql service is running.sudo service mysql status
Example Output:
~ $ sudo service mysql status
mysql start/running, process 4745

B) Check that the mysql_upgrade was successful.sudo mysql_upgrade

Example Output:
~ $ sudo mysql_upgrade
This installation of MySQL is already upgraded to 5.5.61-MariaDB, use --force if you still need to run mysql_upgrade

Step 8: The upgrade is complete, check that your databases exist and are working.

MySQL 5.7 to MariaDB 10.2 on Ubuntu 16.04

Step 1:  Confirm backups are present before proceeding at the scheduled time.

Step 2: Check the local root account has a proper password. Before upgrading to MariaDB 10.2, check the ‘root’ @ ’localhost’ user to ensure a password is assigned otherwise, the auth_socket plugin uses an empty password. This is common practice in older setups and causes problems with the upgrade process due to the default mode of MariaDB 10.2 in Strict SQL.

The following script will print the local root user details.

mysql -e 'select User,Host,Plugin,authentication_string from user where authentication_string = "" and plugin = "auth_socket";' mysql
Example Output:
~ $ mysql -e 'select User,Host,Plugin,authentication_string from user where authentication_string = "" and plugin = "auth_socket";' mysql
+------+-----------+-------------+-----------------------+
| User | Host | Plugin | authentication_string |
+------+-----------+-------------+-----------------------+
| root | localhost | auth_socket | |
+------+-----------+-------------+-----------------------+

Below are two examples of how to update these entries.

Automagic Method: The following one-liner reads the password from /root/.my.cnf and uses that password to update the MySQL user entry, if the file exists.

sudo test -e /root/.my.cnf && sudo mysql -e "ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '$(awk -F"[=']" 'tolower($1)~/password/{print $(NF-1)}' /root/.my.cnf)'; select User,Host,Plugin,authentication_string from user where user = 'root' and host = 'localhost';" mysql || echo “ERROR: /root/.my.cnf does not exist, are you root?”
Example Output:
~ $ sudo test -e /root/.my.cnf && sudo mysql -e "ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '$(awk -F"[=']" 'tolower($1)~/password/{print $(NF-1)}' /root/.my.cnf)'; select User,Host,Plugin,authentication_string from user where user = 'root' and host = 'localhost';" mysql || echo “ERROR: /root/.my.cnf does not exist, are you root?”
+------+-----------+-----------------------+-------------------------------------------+
| User | Host | Plugin | authentication_string |
+------+-----------+-----------------------+-------------------------------------------+
| root | localhost | mysql_native_password | *40C5E49F0CC7BDC637FEEDFBF14FF100C37619D7 |
+------+-----------+-----------------------+-------------------------------------------+if the Automagic method does not work try the manual method.

Manual Method: The following syntax is necessary to add a proper password to the root user account. Don’t forget to update the /root/.my.cnf file with the correct password or your update may encounter errors. Be sure to substitute the correct password for SuperSecretPass.

ALTER USER ‘root’@’localhost’ IDENTIFIED WITH mysql_native_password BY ‘SuperSecretPass’;

Step 3: Install the MariaDB 10.2 repository. This is a multi-command stanza that will install the necessary required tools, GPG key, repository and update the package caches.

sudo apt-get install software-properties-common -y > /dev/null
sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
sudo add-apt-repository 'deb [arch=amd64,arm64,i386,ppc64el] http://ftp.osuosl.org/pub/mariadb/repo/10.2/ubuntu xenial main'
sudo apt-get update > /dev/null

Example Output:
~ $ sudo apt-get install software-properties-common -y
~ $ sudo apt-key adv --recv-keys --keyserver hkp://keyserver.ubuntu.com:80 0xF1656F24C74CD1D8
Executing: /tmp/tmp.J8PdET9w5B/gpg.1.sh --recv-keys
--keyserver
hkp://keyserver.ubuntu.com:80
0xF1656F24C74CD1D8
gpg: requesting key C74CD1D8 from hkp server keyserver.ubuntu.com
gpg: key C74CD1D8: public key "MariaDB Signing Key <signing-key@mariadb.org>" imported
gpg: Total number processed: 1
gpg: imported: 1 (RSA: 1)
~ $ sudo add-apt-repository 'deb [arch=amd64,arm64,i386,ppc64el] http://ftp.osuosl.org/pub/mariadb/repo/10.2/ubuntu xenial main'
~ $ sudo apt-get update > /dev/nullTruncated for brevity.

Step 4: Stop mysql service.

sudo service mysql stop
Example Output:
~ $ sudo service mysql stop
mysql stop/waiting

Step 5: Rename MySQL config file /etc/mysql/my.cnf to /etc/mysql/my.cnf.bak. This step is necessary to ensure all incompatible directives/variables have been removed from the configuration to prevent problems with the install.
sudo mv /etc/mysql/my.cnf{,.bak}Check out incompatible directives.
Step 6: Install the mariadb-server package. This will simultaneously remove the existing MySQL binaries and then install the new MariaDB binaries.

sudo apt-get install mariadb-server -yExample Output:
~ $ sudo apt install mariadb-server -y</code?

Step 7: During the installation an on-screen dialog will appear prompting that the root password could not be changed because one is already in place. Press enter to proceed.

During upgrading MariaDB will state that a password already exists.

Step 8: When completed successfully, the mysql service should automatically start.
sudo service mysql statusExample Output:
~ $ sudo service mysql status
mysql start/running, process 4745

Step 9: Finally, run mysql_upgrade to complete the upgrade.
sudo mysql_upgradeThe output is suppose illustrates normal errors when upgrading.

Example Output:

~ $ sudo mysql_upgrade
MySQL upgrade detected
Phase 1/7: Checking and upgrading mysql database
Processing databases
mysql
mysql.column_stats OK
mysql.columns_priv OK
mysql.db OK
mysql.engine_cost OK
mysql.event OK
mysql.func OK
mysql.gtid_executed OK
mysql.gtid_slave_pos OK
mysql.help_category OK
mysql.help_keyword OK
mysql.help_relation OK
mysql.help_topic OK
mysql.host OK
mysql.index_stats OK
mysql.innodb_index_stats OK
mysql.innodb_table_stats OK
mysql.plugin OK
mysql.proc OK
mysql.procs_priv OK
mysql.proxies_priv OK
mysql.roles_mapping OK
mysql.server_cost OK
mysql.servers OK
mysql.slave_master_info OK
mysql.slave_relay_log_info OK
mysql.slave_worker_info OK
mysql.table_stats OK
mysql.tables_priv OK
mysql.time_zone OK
mysql.time_zone_leap_second OK
mysql.time_zone_name OK
mysql.time_zone_transition OK
mysql.time_zone_transition_type OK
mysql.user OK
Upgrading from a version before MariaDB-10.1
Phase 2/7: Installing used storage engines
Checking for tables with unknown storage engine
Phase 3/7: Fixing views from mysql
sys.host_summary
Error : Table 'performance_schema.memory_summary_by_host_by_event_name' doesn't exist
Error : View 'sys.host_summary' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.host_summary_by_file_io
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.host_summary_by_file_io_type
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.host_summary_by_stages
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.host_summary_by_statement_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.host_summary_by_statement_type
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.innodb_buffer_stats_by_schema
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.innodb_buffer_stats_by_table
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.innodb_lock_waits
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.io_by_thread_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.io_global_by_file_by_bytes
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.io_global_by_file_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.io_global_by_wait_by_bytes
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.io_global_by_wait_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.latest_file_io
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.memory_by_host_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_host_by_event_name' doesn't exist
Error : View 'sys.memory_by_host_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.memory_by_thread_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_thread_by_event_name' doesn't exist
Error : View 'sys.memory_by_thread_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.memory_by_user_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_user_by_event_name' doesn't exist
Error : View 'sys.memory_by_user_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.memory_global_by_current_bytes
Error : Table 'performance_schema.memory_summary_global_by_event_name' doesn't exist
Error : View 'sys.memory_global_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.memory_global_total
Error : Table 'performance_schema.memory_summary_global_by_event_name' doesn't exist
Error : View 'sys.memory_global_total' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.metrics
Error : Table 'performance_schema.global_status' doesn't exist
Error : View 'sys.metrics' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.processlist
Error : Table 'performance_schema.events_transactions_current' doesn't exist
Error : View 'sys.processlist' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.ps_check_lost_instrumentation
Error : Table 'performance_schema.global_status' doesn't exist
Error : View 'sys.ps_check_lost_instrumentation' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.schema_auto_increment_columns OK
sys.schema_index_statistics
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.schema_object_overview OK
sys.schema_redundant_indexes OK
sys.schema_table_lock_waits
Error : Table 'performance_schema.metadata_locks' doesn't exist
Error : View 'sys.schema_table_lock_waits' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.schema_table_statistics
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.schema_table_statistics_with_buffer
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.schema_tables_with_full_table_scans
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.schema_unused_indexes OK
sys.session
Error : Table 'performance_schema.events_transactions_current' doesn't exist
Error : View 'sys.session' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.session_ssl_status
Error : Table 'performance_schema.status_by_thread' doesn't exist
Error : View 'sys.session_ssl_status' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.statement_analysis
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.statements_with_errors_or_warnings
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.statements_with_full_table_scans
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.statements_with_runtimes_in_95th_percentile
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.statements_with_sorting
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.statements_with_temp_tables
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.user_summary
Error : Table 'performance_schema.memory_summary_by_user_by_event_name' doesn't exist
Error : View 'sys.user_summary' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.user_summary_by_file_io
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.user_summary_by_file_io_type
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.user_summary_by_stages
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.user_summary_by_statement_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.user_summary_by_statement_type
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.version OK
sys.wait_classes_global_by_avg_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.wait_classes_global_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.waits_by_host_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.waits_by_user_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.waits_global_by_latency
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.x$host_summary
Error : Table 'performance_schema.memory_summary_by_host_by_event_name' doesn't exist
Error : View 'sys.x$host_summary' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$host_summary_by_file_io OK
sys.x$host_summary_by_file_io_type OK
sys.x$host_summary_by_stages OK
sys.x$host_summary_by_statement_latency OK
sys.x$host_summary_by_statement_type OK
sys.x$innodb_buffer_stats_by_schema OK
sys.x$innodb_buffer_stats_by_table OK
sys.x$innodb_lock_waits OK
sys.x$io_by_thread_by_latency OK
sys.x$io_global_by_file_by_bytes OK
sys.x$io_global_by_file_by_latency OK
sys.x$io_global_by_wait_by_bytes OK
sys.x$io_global_by_wait_by_latency OK
sys.x$latest_file_io OK
sys.x$memory_by_host_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_host_by_event_name' doesn't exist
Error : View 'sys.x$memory_by_host_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$memory_by_thread_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_thread_by_event_name' doesn't exist
Error : View 'sys.x$memory_by_thread_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$memory_by_user_by_current_bytes
Error : Table 'performance_schema.memory_summary_by_user_by_event_name' doesn't exist
Error : View 'sys.x$memory_by_user_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$memory_global_by_current_bytes
Error : Table 'performance_schema.memory_summary_global_by_event_name' doesn't exist
Error : View 'sys.x$memory_global_by_current_bytes' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$memory_global_total
Error : Table 'performance_schema.memory_summary_global_by_event_name' doesn't exist
Error : View 'sys.x$memory_global_total' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$processlist
Error : Table 'performance_schema.events_transactions_current' doesn't exist
Error : View 'sys.x$processlist' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$ps_digest_95th_percentile_by_avg_us OK
sys.x$ps_digest_avg_latency_distribution OK
sys.x$ps_schema_table_statistics_io
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.x$schema_flattened_keys OK
sys.x$schema_index_statistics OK
sys.x$schema_table_lock_waits
Error : Table 'performance_schema.metadata_locks' doesn't exist
Error : View 'sys.x$schema_table_lock_waits' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$schema_table_statistics
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.x$schema_table_statistics_with_buffer
Error : Cannot load from mysql.proc. The table is probably corrupted
error : Corrupt
sys.x$schema_tables_with_full_table_scans OK
sys.x$session
Error : Table 'performance_schema.events_transactions_current' doesn't exist
Error : View 'sys.x$session' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$statement_analysis OK
sys.x$statements_with_errors_or_warnings OK
sys.x$statements_with_full_table_scans OK
sys.x$statements_with_runtimes_in_95th_percentile OK
sys.x$statements_with_sorting OK
sys.x$statements_with_temp_tables OK
sys.x$user_summary
Error : Table 'performance_schema.memory_summary_by_user_by_event_name' doesn't exist
Error : View 'sys.x$user_summary' references invalid table(s) or column(s) or function(s) or definer/invoker of view lack rights to use them
error : Corrupt
sys.x$user_summary_by_file_io OK
sys.x$user_summary_by_file_io_type OK
sys.x$user_summary_by_stages OK
sys.x$user_summary_by_statement_latency OK
sys.x$user_summary_by_statement_type OK
sys.x$wait_classes_global_by_avg_latency OK
sys.x$wait_classes_global_by_latency OK
sys.x$waits_by_host_by_latency OK
sys.x$waits_by_user_by_latency OK
sys.x$waits_global_by_latency OK
Phase 4/7: Running 'mysql_fix_privilege_tables'
Phase 5/7: Fixing table and database names
Phase 6/7: Checking and upgrading tables
Processing databases
information_schema
performance_schema
sys
sys.sys_config OK
Phase 7/7: Running 'FLUSH PRIVILEGES'
OK

performance_schema and mysql.pc are normal errors when updating MySQL.Step 10: The upgrade is complete, check that your databases exist and are working.

MySQL Performance: System Configuration File & Routine Maintenance

Posted on by J. Potter
Category: Series | Tags: , , ,

The majority of work needed when adjusting the MySQL server is editing the applicable directives within a MySQL configuration file. There are multiple, optional configuration files that MySQL looks for when starting up. They are read in the following order:

MySQL Configuration Files:

MySQL Configuration Files:

1./etc/my.cnf

2./etc/mysql/my.cnf

3.SYSCONFDIR/my.cnf

4.$MYSQL_HOME/my.cnf

5.~/.my.cnf

Any of these files can contain MySQL server directives. For the sake of simplicity, this article assumes the default file /etc/my.cnf is being used for all examples. This is the most widely known file path in the majority of cases. However, some Linux distributions favor others than the ones listed from above. Though the file location is changed in these other distributions, the syntax and recommendations in this article series apply equally to all Linux based systems.

 

MySQL Configuration File Syntax

Each entry inside the configuration file applies to the most recent section header. Section headers are made up of a single line with the name of the header encapsulated within square brackets (e.g. [name]). When optimizing the MySQL service daemon,  changes will need to be within in the [mysqld] section header. The example below illustrates how this should look.

Example: Configuration File Syntax

[mysqld] innodb_buffer_pool_size=2G
innodb_buffer_pool_instances=2

Note
The trailing d character after mysql is required to apply settings to the MySQL service daemon. The [mysql] header without a trailing d character is incorrect and applies only to MySQL client.

 

Applying MySQL Config Changes

The vast majority of directive changes merely require a restart of the MySQL service. There are a handful of other directives which may require an additional task to be undertaken while the MySQL service is offline. These tasks will be outlined in their specific section later in the article.

Restart MySQL Service:

service mysql restart

Important:
Refrain from making several optimization changes to your existing MySQL config at one time. This is especially true when adjusting production level servers. Making small incremental changes will make it easier to identify problems with individual changes and isolate settings that may not work well for your unique setup.

Routine Maintenance

In the follow-up articles to this part of the MySQL Performance series, we will be outlining several directives and some suggested techniques to use for configuring those directives. It is imperative to understand that MySQL Optimization is an ongoing, ever-evolving configuration. As sites grow, so do data sets and workload behavior. The settings you configure today, will eventually become obsolete and probably sooner than you would like. Because of this eventuality, it is vitally important that routine maintenance is conducted on your configuration.

What are some tasks to perform routinely:
  1. Reevaluate all buffers and directives that have been modified previously. This includes the changes discussed and recommended in the entirety of this article series.
  2. Reassess MySQL Query Statistics to determine workload behaviors.
  3. Reassess tablespace data, rate of growth or other trends in data consumption.
  4. Archive old data from large or heavy trafficked tables to ease the burden of read/write requests to those tables.
  5. Reevaluate indexes and their performance. Create new, better indexes and remove old, unused indexes.

Performance Expectations

Although, the changes recommended in this article series aim to squeeze the best performance out of MySQL, the performance increase you may see is entirely subjective. Following these recommendations should help smooth the edges on any servers hitting the bottlenecks they are designed to target. However, there is no guarantee that these changes will have a positive or noticeable impact on the application level.

The biggest issues facing application performance are often on the coding level and not the server level. The underlying MySQL server configuration only carries application performance so far. Identifying problematic queries and inefficient coding practices that serialize your workload are problems that even a finely tuned MySQL server configuration just cannot correct. If you are in doubt, or your application performance seems to suffer despite all the server level optimization in the world, then you’re probably hitting code level performance problems, and we recommend contacting a qualified Database Administrator (DBA) to evaluate your application performance properly.

MySQL Performance: InnoDB Buffers & Directives

Posted on by J. Potter
Category: Series | Tags: , , , ,

As discussed earlier in our MySQL Performance series, the InnoDB storage engine is designed to be a high-performance database for very large datasets. The row-locking technique it uses allows for many read and write requests to occur on a single table concurrently. This is a vast improvement in speed over traditional table-locking of the MyISAM engine. This part of our MySQL Performance series will focus on configuring InnoDB tables for maximum concurrency with minimal disk input/output (I/O).

Disk I/O & Temporary Tables

Disk I/O & Temporary Tables.

A simple and effective change that can provide a noticeable performance boost immediately is the practice of forcing all temporary table writes into memory instead of writing to a hard disk. Writing temp tables to RAM reduces the impact MySQL has on overall system disk I/O, which greatly improves performance. This change is done by leveraging the /dev/shm tmpfs partition in Linux. This special device gives server processes the ability to write files directly into RAM as if it were a standard disk drive.

 

InnoDB Log File Size

InnoDB Log File Size

The InnoDB log file is not your traditional log file. It’s a special binary redo log, which InnoDB uses to store redo activity for every write request handled by the server. Every write query executed gets a redo entry in the log file so that change can be recovered in the event of a crash. Because of this reason, the InnoDB log file size plays a critical role in MySQL write query performance, particularly on write-heavy databases.

Rule of Thumb: innodb_log_file_size
MySQL®️ Recommends: “The larger the value, the less checkpoint flush activity is required in the buffer pool, saving disk I/O.” A log file size of 1GB is sufficient for most situation. This may need to be raised when database growth exceeded several dozen GB in size.
Notice
MySQL®️ Warns: “Larger log files also make crash recovery slower, although improvements to recovery performance make log file size less of a consideration than it was in earlier versions of MySQL. “

Due to the special nature of the InnoDB Redo Logs, this setting cannot be changed without first deleting the existing InnoDB log files. The following procedure for adjusting the innodb_log_file_size directive must be followed before MySQL will start again.

Changing innodb_log_file_size Procedure:

  1. Stop MySQL Serviceservice mysql stop
  1. Update innodb_log_file_size within [mysqld] header in /etc/my.cnf file.innodb_log_file_size=1G
  1. Move the existing log files out of the mysql directorymv /var/lib/mysql/ib_logfile* /backup
  1. Start MySQL Serviceservice mysql start

 

InnoDB Buffer Pool (IBP)

The InnoDB Buffer Pool plays a critical role in MySQL Performance. The IBP is a reserved portion of system memory where InnoDB table and index data are cached. This allows frequently accessed data to be returned quickly, without the need of spinning up a physical hard drive. The more InnoDB tablespace that is cached in memory, the less often MySQL will access physical disks, which manifests as faster query response times and improved overall system performance.

There are multiple directives which control IBP behavior. Tuning these to match the servers existing tablespace data, with some room to grow, will optimize the performance of any queries using InnoDB tables. Since InnoDB is the recommended engine for very large tables, optimizing the IBP gives major performance gains.

 

InnoDB Buffer Pool Size

InnoDB Buffer Pool Size

The larger the IBP, the more InnoDB functions as a high-performance in-memory database. However, setting the size too large can be detrimental to overall system performance. A balance must be struck between the IBP size and needed memory for other system services. In an ideal configuration, the IBP should be as large as possible, without causing excessive swapping (i.e., Thrashing) to occur. There are some simple rules to follow when making these determinations.

Rule of Thumb: innodb_buffer_pool_size (Dedicated Servers)

‣When MySQL is the only major service on a server.

The recommended configuration by MySQL is for innodb_buffer_pool_size to use as much as 80% of the system’s total physical memory.

Calculate innodb_buffer_pool_size Script: (Dedicated Server)

awk '
/MemTotal/{
$3="GB"
$2=sprintf("%.0f",$2/1048576)
print
$1="  Mem80%:"
$2=sprintf("%.0f",$2*.8)
print
}' /proc/meminfoExample Output:

MemTotal: 15 GB
Mem80%: 12 GB

Rule of Thumb: innodb_buffer_pool_size (Shared Servers)

‣When MySQL runs alongside other major services like Web, Email, etc... (e.g. cPanel, Plesk)

Due to their varied resource requirements, there is no one-size-fits-all calculation for shared servers. It becomes necessary to calculate the memory requirement needs of all other critical services on the server and subtract those from total system memory to find a proper amount of available memory which can be assigned to innodb_buffer_pool_size.

A simplified method is to use a generic calculation. A conservative starting point is assigning between 30 and 80 percent of available system memory, instead of total physical memory. However, determining the exact setting may require some guesswork and testing.

The following awk script reads MemAvail from /proc/meminfo and provides a selection of percentage based calculations to choose for the server.

Calculate innodb_buffer_pool_size Script: (Shared Server)

awk '
/MemAvail/{
$3="G";_=$2
$2=sprintf("% 3.0f",_/1048576)
print
for (i=80;i>=25;i-=10) {
$1="MemAvail_"i"%:"
$2=sprintf("% 3.0f",_*(i/100)/1048576)
$4=sprintf("| %.0f M",_*(i/100)/1024)
print
}
}' /proc/meminfo

Example Output:

MemAvailable:  10 G
MemAvail_80%:   8 G | 8405 M
MemAvail_70%:   7 G | 7354 M
MemAvail_60%:   6 G | 6304 M
MemAvail_50%:   5 G | 5253 M
MemAvail_40%:   4 G | 4203 M
MemAvail_30%:   3 G | 3152 M

 

InnoDB Buffer Pool Instances

InnoDB Buffer Pool Instances

The innodb_buffer_pool_instances directive controls the number of memory pages Innodb creates. MySQL ignores this directive unless the innodb_buffer_pool_size is greater than 1G/1024M. When larger than 1G, the buffer pool is divided up into a number of equal sized memory pages specified by this directive.

Rule of Thumb: innodb_buffer_pool_instances
MySQL®️ Recommends: “For best efficiency, specify a combination of innodb_buffer_pool_instances and innodb_buffer_pool_size so that each buffer pool instance is at least 1GB.”

  ‣ Rule Exception: innodb_buffer_pool_instances should not exceed Total_IO_Threads

Total_IO_Threads=(innodb_read_io_threads + innodb_write_io_threads)

Preference a 1:1 Ratio for: Total_Instances:Total_IO_Threads

 

InnoDB I/O Threads

InnoDB I/O ThreadsInnoDB I/O Threads

Input/Output threads are sub-processes of MySQL which directly access the IBP memory pages. There are two types of I/O threads: innodb_read_io_threads and innodb_write_io_threads. These threads read and write, respectively, to the individual memory pages created by innodb_buffer_pool_instances.

The default value for both of these thread types is 4, making a total of 8 threads running concurrently. This pairs up with the default number of memory pages created when innodb_buffer_pool_size is larger than 1G (x8). This synergy is a key factor when improving InnoDB performance on very large database servers with large volumes of RAM and CPU cores. When increasing innodb_buffer_pool_instances past the default of 8, it becomes optimal to increase the number of threads to handle the extra memory pages concurrently. The goal being, to keep the synergy of total I/O threads equal to total memory pages:

( innodb_read_io_threads + innodb_write_io_threads ) = innodb_buffer_pool_instances

When to change InnoDB I/O Threads

Two conditions should be satisfied before adjusting I/O threads for a server.

  1. When innodb_buffer_pool_size is larger than 8 Gigabytes, this means there are more memory pages than I/O threads to handle them concurrently.
  2. When the server has more than 8 CPU cores to devote to the MySQL Service.

It is not enough to merely divide the innodb_buffer_pool_instances in half to get equal numbers of read and write threads. The goal is to increase the number of threads primarily used by the specific server’s query workload. For instance, if your server reads more data than it writes, increasing write threads would be counter-productive. The same holds true in reverse.

How to Calculate MySQL Read:Write Ratio

The global statistics kept by a MySQL server can be leveraged to determine a systems Read:Write Ratio. The following MySQL queries can be used to calculate the Total_Reads and Total_Writes of a server.

Total_Reads = Com_select

SHOW GLOBAL STATUS LIKE 'Com_select';

Total_Writes = Com_delete + Com_insert + Com_replace + Com_update

SHOW GLOBAL STATUS WHERE Variable_name IN ('Com_insert', 'Com_update', 'Com_replace', 'Com_delete');

  • If the Total_Reads is greater than Total_Writes, the server is considered Read_Heavy.
  • If the Total_Writes is greater than Total_Reads, the server is considered Write_Heavy.

The following awk script will print the necessary statistics variables from MySQL and automatically calculate a simplified Read:Write Ratio to help determine whether the system in question is Read_Heavy or Write_Heavy.

Calculate Read:Write Ratio Script:

mysql -e 'SHOW GLOBAL STATUS;'|\
awk '
$1~/Com_(delete|insert|update|replace)$/{
w += $2
printf $0 "\t + Total_Writes = " w "\n"
}
$1~/Com_(select)/{
r += $2
printf $0 "\t + Total_Reads = " r "\n"
}
END {
printf "\nRead:Write Ratio:\n\t" r ":" w " "
if (r >= w) {
R=sprintf("%.0f",r/w)
print R ":1"
} else {
W=sprintf("%.0f",w/r)
print "1:" W
}
}'

Example Output:

Com_delete    14916     + Total_Writes = 14916
Com_insert    87413     + Total_Writes = 102329
Com_replace   0         + Total_Writes = 102329
Com_select    675528    + Total_Reads = 675528
Com_update    18976     + Total_Writes = 121305
Read:Write Ratio:
675528:121305 6:1

Note:
Adjust the first line’s mysql statement as needed to connect to the appropriate server. e.g.,

mysql -h localhost -u root -p -e 'SHOW GLOBAL STATUS;' |\

Hardware CPU Core Considerations

When adjusting innodb_read_io_threads or innodb_write_io_threads, keep the total threads between the two equal to the number of CPU cores available to MySQL. This ensures maximum concurrency as each memory page can be accessed simultaneously by each individual CPU core.

Rule of Thumb: InnoDB I/O Threads (High-Performance) ‣innodb_read_io_threads + innodb_write_io_threads
The total number of InnoDB I/O Threads should not surpass the total number of CPU cores available to MySQL.

When increasing Innodb I/O Threads, increase only the read or write threads depending on whether the server is Read_Heavy or Write_Heavy.

Other Directives

There are several more advanced techniques for fine tuning the InnoDB Buffer Pool and its behavior. These are beyond the scope of this article. However, you can find more details about these techniques on the MySQL website here: 15.5.1 Buffer Pool.