MySQL Architecture – Components (How MySQL Works Internally)

MySQL Architecture – Components (How MySQL Works Internally). This article discusses internal works of MySQL components.

First of all, MySQL is an open source, Oracle backed relational database management system (RDBMS) based on Structured Query Language (SQL). Well, it runs on all major platforms, including Windows, Linux, and UNIX. Although you apply it across a wide range of applications, MySQL is most commonly associated with online publishing and web applications.

All in all, MySQL is a critical component of the LAMP stack. LAMP is a web development platform that implements Linux as the operating system, MySQL as the relational database management system, Apache as the web server, and PHP as the object oriented scripting language. However, sometimes Python or Perl is used instead of PHP. Independent developers use MySQL under the GNU General Public License, but businesses must acquire a commercial license from Oracle.

Shall we start this article blog about how MySQL works internally, including its components and top features. Read on!

How MySQL Works

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Altogether, MySQL follows a client-server model. The heart of MySQL is the MySQL server which manages all of the database commands or instructions. Basically, MySQL server is available as a library that users embed into separate applications and as an independent program for client server network environments.

Besides, MySQL operates with multiple utility programs that support the administration of MySQL databases. Users send commands to the MySQL server through the MySQL client on a computer.

Also, the MySQL’s design enables it to manage large databases quickly. Although MySQL usually resides on a single machine, it sends the database to several locations, as users can access it through different MySQL client interfaces. These interfaces transfer SQL statements to the server and then displays the results.

Components of MySQL (Internal Works)

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Certainly, MySQL architecture consists of three layers or ends. The layers of the architecture include the query execution end (or client end) at the top, a server resource end at the middle, and the storage engine at the bottom.

The database architecture defines the interaction and relationship between the storage end, the client end, and the client end of the system. Below we discuss the various layers in detail.

1. Client End

Here, the client end of the MySQL structure is the component that end users of the database system interact with. You submit multiple MySQL commands to the server via the command prompt or the graphic user interface.

For each valid command submission, a valid output displays on the screen. For each wrong command submission, the system relays an error notification as feedback to the screen. Some of the critical services rendered by the Client end are :

Connection handling

When you submit a request to the server end, the server acknowledges the request. A connection establishes immediately to allow you to execute more requests. This functionality is referred to as connection handling and is a feature of the client side of the structure.


Authentication happens on the server side when users connect to the MySQL server. The client end component accomplishes authentication with the aid of a username and password.


After authentication, the users successfully connect to the MySQL server. After that, the server checks if a particular user has the necessary privileges required to make specific queries against the MySQL server.

2. Server End

The second layer of MySQL architecture is also known as the “Brain of MySQL Architecture.” This is because this layer controls all the logical functionalities of MySQL’s relational database management system. When a client submits requests to the server, the server provides an output as soon as it matches the instruction.


The sub components of MySQL server include:

Thread Handling

After a client sends a successful request to the server, the server accepts the request, and the client connects. This kind of connection is known as a thread. The server end of the architecture helps to handle each thread in a process known as thread handling. The thread handling functionality executes via the server end of the architecture. Also, the thread handling module also manages the client side queries executed by the thread.


Data within a database is broken down into several tokens by an operation known as lexical analysis. The parser is a software component that generates a data structure/parse tree of a given input.

Afterwards, MySQL‘s parser comprises the grammar rule module and the lexical scanner. The lexical scanner breaks the entire input into tokens, while the grammar rule module looks for a combination of SQL grammar rules that create this sequence and runs the code associated with those rules. Finally, the parser generates a parse tree, which the optimizer can use. Contrary to some parsers, which convert the query’s textual representation into byte code, MySQL’s parser translates it into internal interlinking C++/C structures within the program memory.


Once the parsing is complete, the system applies different types of optimization techniques at the optimizer block. These techniques might include query rewriting, proper index selection, and order of scanning the tables. Here, the MySQL uses a cost based approach to optimization.

Certainly, MySQL attempts to predict the cost of different execution plans and select the cheapest. Initially, the unit of the cost was a single arbitrary 4 KB data page read. However, it has become more complex and includes factors like the cost of running a WHERE clause comparison.

Query Cache

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The query cache stores the entire result collection for input query statements. Before parsing a query, the server consults the query cache, which only stores SELECT statements and their result sets. If a user submits a query similar to one already in the cache, the server skips the parsing, optimization, and execution of queries. The server just relays the result set it had previously stored.

Afterwards, MySQL initializes and assigns a specific amount of memory for the query cache simultaneously when the server starts from a value allocated to the variable ‘query_cache_size.’ If you update this variable or set it to its current value, MySQL deletes all cached queries, breaks the cache to specific sizes, and restarts the cache memory.

Buffer and Cache

This sub component stores the previous problem or query expressed by users. When clients write a query, it initially goes to the query cache, which checks to see if that same problem or query is available in the cache. If an identical query is available, the system provides an output without involving the parser and optimizer.

Table Metadata Cache

The metadata cache is an isolated section of memory that tracks information on objects, databases, and indexes. The number of open databases is directly proportional to the metadata size. The more open indexes, objects, or databases, the bigger the metadata cache size.

Key Cache

A key cache sub-component is a cache mechanism that contains the most frequently accessed index block. Many database management systems use this approach to minimize disk I/O since memory is faster than hard drives.

3. Storage End

Storage end of MySQL database has a unique kind of storage engine generated by the system depending on the different situations and needs of databases. The storage engines contain all the user created tables inside the database. As a result, the storage end enables the retrieving and storing of MySQL data. Concurrently, the storage engine comes with an API that helps execute queries from the client end of the system by passing rows back and forth in it.

Features of MySQL

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As noted, MySQL is the most commonly used RDBMS in many organizations that process large amounts of data. Some of its handy features include:

MySQL is Highly Compatible

Although it is most famous for assisting developers in maintaining web services and internet applications, MySQL is also highly compatible with other architectures and technologies. The RDBMS operates all the leading computing platforms, such as Windows, Linux, Mac OS, and Unix.

The client server architecture enables MySQL to support different programming interfaces, as well as a variety of back-ends. Users directly transfer data from MySQL to its forks. Additionally, MySQL also migrates data directly from many other RDBMSs because of the architectural and language similarities.

Various third party and Oracle migration tools enable MySQL to transfer data to and from a massive set of available storage systems. Well, MySQL does this regardless of whether the storage systems are on premises or reside in the cloud. Simply put, MySQL integrates with all virtualized environments and functions as independent portable libraries for small applications, testing, and learning purposes. Conversely MySQL’s high compatibility with all these technologies makes it the most practical choice for RDBMS.

MySQL Databases are Relational

The critical difference between relational databases and other digital storage systems is the organization of data at a high level. Databases like MySQL contain records in several individuals, highly codified tables instead of a single general repository or sets of semi structured and unstructured documents.

This enables RDBMS to optimize actions such as information updates, data retrieval, or more advanced actions like aggregations. A logical model defines all of the contents in the database. The model describes how indices from two tables relate, the characteristics of views and tables, or each column’s value limit.

Open Source and Free for Use

Any individual or business may freely use, publish, expand, and modify the open source MySQL code base. Enterprises that need to integrate or include a commercial application to MySQL code can buy a commercially licensed version. 

These MySQL options provide organizations with extra flexibility. The public and communal nature of open-source releases improve MySQL’s online support culture and documentation and ensure its capabilities keep up with current user needs.

Easy to Configure and Use

Although MySQL’s relational nature and rigid storage structures might seem to limit it, the tabular paradigm is, in fact, very intuitive and allows for more excellent usability.

Generally, MySQL supports a wide variety of data structures, such as numeric, standard, date, alphanumeric, and time types, to more complex geospatial or JSON data. Apart from the expansive in built feature set and data types, the MySQL environment also contains various tools that ease reporting, data analysis, and data management.

Despite the RDBMS’s overarching architecture, you can still find a MySQL feature that allows you to codify and model data however you wish. Hence, MySQL is one of the most straightforward database technologies to learn and implement.

Pros of MySQL

  • More secure since it consists of a solid layer protecting sensitive data from interlopers.
  • Highly accessible to all users for free since it is open-source software.
  • Contains a unique storage mechanism that makes it cheaper, faster, and more reliable.
  • Highly scalable and capable of managing over 50 million rows.
  • Enables the system to roll back transactions.

Cons of MySQL

  • Lacks a good development and debugging tool.
  • MySQL versions lower than 5.0 do not support COMMIT, stored procedure, and ROLE.
  • Not suitable for live streaming.

Thank you for reading MySQL Architecture – Components (How MySQL Works Internally). We shall conclude this article blog now.

MySQL Architecture – Components (How MySQL Works Internally) Conclusion

To conclude, MySQL is a widely used, time tested, fully featured, and modern relational database management system. Organizations everywhere implement it for mission critical business data processing and storage, as a back end to popular consumer facing applications, and as part of robust web software stacks. Whether your enterprise currently uses MySQL or is considering migrating to this RDBMS, the significance of data integration can not be overstated.

Please navigate to more MySQL content, check out our blog over here

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Dennis Muvaa

Dennis is an expert content writer and SEO strategist in cloud technologies such as AWS, Azure, and GCP. He's also experienced in cybersecurity, big data, and AI.

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