SQL Server Architecture - Detailed Explanation

SQL server is an efficient system that supports organizing and accessing a large quantity of data seamlessly. In its basic form, the SQL server has a client-server architecture. It accepts client requests, processes, and responds to the client effectively. This architecture has three essential components a protocol layer, a relational engine, and a storage engine. The protocol layer supports three types of client-server architectures. A relational engine is also called a query processor. And storage engine stores data in the storage systems.

Mainly, SQL server architecture provides multiple advantages to its users. Mainly, you can provide different instances for development, production, and test environments. Because of this feature, you can significantly prevent recurring security problems. Moreover, you can analyze data using SQL server analysis services and create reports using SQL server reporting services with the help of SQL server architecture.

Curious to learn more about SQL Server Architecture? In this blog, you can learn the history of SQL servers, the components of SQL server architecture, and their advantages in a detailed way.

SQL Server Architecture - Table of Contents

The History of SQL Server What is an SQL Server? Why SQL Server? SQL Server Architecture SQL Server Network Interface(Protocol Layer) Relational Engine Storage Engine Advantages of SQL Server FAQs Conclusion

The History of SQL Server

Microsoft introduced the SQL server 1989, a relational database system. Now, you can see a brief SQL of  history below:   

• It started with SQL Server 1.0 in 1989 and continued to release updates written in different codes.
• Multiple SQL server versions were released between 1992 and 2012 but are inactive now. SQL server 12.0 is the table version used by industries today (Released in 2014).
• Most of the SQL server releases support x32 processors, but the versions released later in the year 2000 support x64 processors.
• A stable release of Microsoft SQL Server in 2019 has advanced features encouraging enterprises to adopt SQL servers.

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What is an SQL Server?

SQL Server is a Relational Database system that stores raw data. That’s why users can organize and interact with the database using SQL language. With SQL, you can manage a large volume of data seamlessly. Data is stored in an SQL server in table form. Overall, SQL server offers high-performance data storage and access.

You can install one or more SQL servers on a computer. And the servers can have one or more databases. Databases are stored in file systems and further divided into file groups.

Related Article: SQL Server Tutorial

Why SQL Server?

An increase in internet users led to the creation of a large quantity of data globally. So, enterprises need to save, process, and analyze the data to deliver better industry services. SQL Server helps manage this data to store and process effectively and is equipped with in-built data compression and encryption feature.

 

 

 

 

SQL Server Architecture

As you know, SQL Server is a client-server-based model used to process client requests. SQL server architecture consists of three primary components to handle different SQL requests made by the client using other protocols.

Three main components of the SQL Server Architecture are

1. SQL Server Network Interface(Protocol Layer)
2. Relational Engine
3. Storage Engine

We will explore each of these components in detail in the following.

 

 

1. SQL Server Network Interface(Protocol Layer)

If there is a request from a client, then this request can be made through three different types of client-server services.

• Shared memory requests

A client enables requests from the server in the location where the client uses the shared memory.

• TCP/IP requests 

A client enables request service from the server away from the server location and accesses the server using TCP/IP network protocols.

• Named Pipe requests

A client enables this request when the client and server are located on the same intranet.

2. Relational Engine

A relational engine, also known as a query processing unit, consists of three major components to process a client query. Note that a relational engine is responsible for memory, thread, buffer, and task management throughout the request processing.

• Query parser

A query parser is also known as a CMD parser. It helps in parsing the query and checks for any syntactic or semantic errors, thereby creating a query execution tree if no errors are found.

Syntactic errors result from incorrect syntax or typing in the client request.

Semantic errors are caused when there is a mismatch between the tabular columns requested by users.

• Query optimizer

Essentially, a query optimizer is not mandatory for all queries. A client request which consists of DML commands like SELECT, INSERT, UPDATE, or DELETE is sent to the query optimizer to opt for the best execution plan. Then, the optimizer picks the plan that takes less CPU and memory, and I/O inputs to execute. It is performed in three phases as follows:         

1. Pre-Optimization Phase: At times, there exists a query that may take more cost to search for the optimized plan. Then, the optimizer skips the phase of selecting a trivial plan and directly sends the query to the second phase.
2. Transaction Processing Phase: The optimizer finds an optimized transaction processing plan and incorporates one index per table. Sometimes there exists a complex processing plan for the queries where simple processing plans are not found.
3. Parallel Processing and Execution Phase: Optimizers always aim to use low-cost execution and may use the above methods to find an optimal execution. If the above phases cannot find the best way to reduce the query run time, it starts with parallel execution depending on machine resources. Once the plan is ready, the query optimizer sends the request to the executor.

• Query Executor

The Query Executor is responsible for accessing the data from the storage engine and forwarding it to the SNI, which serves the response to the client/user.

3. Storage Engine

It is one of the essential parts of SQL Server architecture. The storage engine takes up all the storage and retrieval of data activities when the client requests. It consists of three major components to process the request. Each component has primitive roles and resources attached to perform when processing a query. We will explore each component in detail.

• Access Manager

The storage manager takes the request from the query executor and sends them to the different access methods. The access methods check whether the query consists of a SELECT or NON-SELECT (UPDATE, ADD, DELETE) request. If a SELECT statement requests data from the database, the access method calls for the buffer manager to proceed further. In the case of the NON-SELECT statement, the query processing is managed by the transaction manager. 

• Transaction Manager

Non-select queries from the access manager are forwarded to the transaction to serve the request. It also interacts with the lock and log manager and uses transaction logs to track every query executed.

• Buffer Manager

Buffer manager takes select queries to execute and uses plan cache, data parsing, and dirty pages to serve the request.

1. Plan Cache: It stores the execution plan temporarily, with which the buffer manager can execute it. In general, these plans in the cache help faster execution of the queries when made more than once.
2. Data Parsing: If there is a plan in the plan cache, it helps the data parser to perform soft parsing, which takes data from the stored cache. In case there is no plan in the plan cache, then complex parsing is done that may take more I/O operations and load data from the data storage.

SQL Operating Systems

SQL Server engine layer follows the application layer with the SQL operating system, which will handle the following critical operations during client-server request processing.

• Performs thread synchronization and scheduling to acquire maximum CPU performance with minimal I/O operations.
• Manages allocation and memory
• focus on exceptional handling and event tracking.
• Analyse and avoid deadlocks.

Related Article: SQL Server Interview Questions

Advantages of SQL Server

The SQL Server Architecture is designed to store and access data on the network. The following are the primary advantages that made many industries adopt SQL servers for their data operations:

• Easy to Install: You can easily install Microsoft SQL Server using the GUI and with a single-click installation procedure. A user-friendly installation procedure keeps it easy to install, unlike any other server installation. It requires heavy command lines and coding basics
• Better Performance: Data storage and retrieval using an MS SQL server are made easy with its inbuilt compression and encryption features making it the best-performing server while handling massive data over any network.
• Advanced Security: Robust security by complex encryption algorithms is used in SQL servers, making them the safest database server. Microsoft-secured server avoids attackers who target open-source databases, making them less vulnerable to unauthorized actions on the database.
• Data Restoration and Recovery made Easy: Microsoft ensures the importance of data and erroneous actions happening with the industries. Hence, making the data restoration and recovery mechanism is one of the critical features of the SQL database server.

SQL Server Architecture FAQs

1. What is a Relational Database System?

In this database system, data is stored in table form. SQL Server is a relational database system. The data in the relational database are related to each other. Keys are used in a relational database to relate records.

2. What is Database Architecture?

It describes the design of a database. Every database architecture consists of models, policies, rules, and standards. Based on these aspects, data is gathered, stored, arranged, and integrated with the database architecture.

3. What is the Architecture Model of an SQL Server?

Client-server is the architecture model of the SQL server.

4. What is a Client-Server Architecture in an SQL server?

The SQL server processes the requests from various clients, and a response is given to the clients. In this architecture, the user can interact with the server using queries. The queries are transferred to the server with the help of different protocols.

5. What is SQLOS?

SQLOS is nothing but an SQL operating system. It performs operations such as exception handling and synchronization services.

Conclusion

So far, you have explored the Microsoft SQL server architecture understanding its actions while serving a client-server request. You have thoroughly studied the various components of SQL server architecture and its uses. You might have understood the importance of SQL server architecture through its advantages. To explore more about SQL Server architecture, you can visit the SQL Server Training page, to achieve excellence in this domain.