How to Load data from SQL Server to Snowflake 

How to Load data from SQL Server to Snowflake 

September 12, 2023
September 12, 2023
How to Load data from SQL Server to Snowflake 
In this article, we will deep dive to have a clear understanding of SQL Server, Snowflake, methods by which loading data from SQL server to Snowflake can be achieved and various technical aspects will be discussed so that you can have a better understanding which type of method would be suitable for you.

Loading data from Microsoft SQL Server to Snowflake involves transferring structured data from a traditional on-premises or cloud-based SQL Server database to a modern cloud-based data warehousing platform. This process enables organizations to leverage Snowflake's powerful analytics capabilities, scalability, and cost-effective cloud infrastructure for processing and analyzing their data. By building a seamless data pipeline, businesses can find new insights and make more data-driven decisions. 

In this article, we will deep dive to have a clear understanding of SQL Server, Snowflake, methods by which loading data from SQL server to Snowflake can be achieved and various technical aspects will be discussed so that you can have a better understanding which type of method would be suitable for you.


Introduction to SQL Server

SQL Server is a relational database management system (RDBMS) designed to store, retrieve, and manage structured data which was developed by Microsoft. It is a comprehensive and enterprise-level database platform used by organizations for a wide range of applications.

Key features of SQL Server

Here are some key features of SQL Server:

  • Relational database management system (RDBMS): SQL Server is built on a relational database model, which organizes data into tables consisting of rows and columns. It supports relations between tables and ensures data integrity using constraints.
  • Transact-SQL (T-SQL): SQL Server uses a customized SQL dialect called Transact-SQL. It extends the standard SQL language with additional features like stored procedures, triggers, and more.
  • Security: It provides diverse security features, including role-based access control, encryption, and auditing, to protect sensitive data.
  • Scalability and performance: SQL Server is designed to handle both small-scale applications and large-scale enterprise solutions. It offers features like parallel query processing, partitioning, and indexing for optimized performance. SQL Server offers features like AlwaysOn Availability Groups, failover clustering, and database mirroring to ensure smooth operations and speedy disaster recovery.
  • Data warehousing capabilities and business intelligence: SQL Server provides tools and features for building and managing data warehouses. This includes features like columnstore indexes and support for data warehousing architectures. It includes services like SQL Server Integration Services (SSIS) for ETL processes, SQL Server Analysis Services (SSAS) for online analytical processing (OLAP), and SQL Server Reporting Services (SSRS) for creating reports.
  • Integration with microsoft ccosystem: SQL Server seamlessly integrates with other Microsoft products and services, such as Azure, .NET framework, SharePoint, and Excel, allowing for a unified ecosystem.
  • Support for JSON and XML: SQL Server provides native support for handling JSON and XML data formats, allowing for hassle free integration with web services and modern application architectures.
  • Developer-Friendly: SQL Server provides a range of development tools, including SQL Server Management Studio (SSMS) for database administration and Visual Studio for application development which makes it convenient to use.
  • Comprehensive support and community: Microsoft offers extensive documentation, forums, and resources for SQL Server. Additionally, there is a large community of developers and administrators who actively contribute to discussions and provide assistance.
  • Variants and editions: SQL Server comes in different editions, including Express (free), Standard, and Enterprise, each designed for different usage scenarios and resource requirements.

SQL Server is widely used in enterprise environments, powering a wide range of applications from small business databases to large-scale, mission-critical systems. It's a versatile and powerful tool for managing structured data.

Introduction to Snowflake 

Snowflake is a cloud-based data warehousing platform that provides a modern and highly scalable solution for storing, processing, and analyzing large volumes of data. It is designed to handle data from multiple sources and support various types of workloads, including data analytics, data engineering, and data science.

Key features of Snowflake 

Here are some key features of Snowflake:

  • Cloud-native architecture: Snowflake is built entirely for the cloud, meaning it leverages the scalability, elasticity, and cost-effectiveness of cloud infrastructure. It can run on major cloud platforms like AWS, Azure, and Google Cloud Platform.
  • Separation of compute and storage: Snowflake's architecture separates storage from compute resources. This allows for independent scaling of storage and compute, providing cost efficiency and flexibility in managing resources.
  • Multi-cluster architecture: Snowflake can simultaneously support multiple virtual warehouses (compute clusters) for different workloads. Each virtual warehouse can have its own configuration, making it suitable for a wide range of use cases.
  • Automatic scaling: Snowflake can automatically scale compute resources up or down based on the workload demands. This ensures optimal performance and cost efficiency, as resources are only used when needed.
  • Data sharing: Snowflake enables easy and secure sharing of data between different accounts and organizations. This feature is particularly useful for collaborative analytics and data exchange.
  • Support for structured and semi-structured data: Snowflake can handle structured data (like tables) as well as semi-structured data formats like JSON, Avro, and Parquet. This flexibility allows for efficient handling of diverse data types.
  • Data cloning and time travel: Users can create copies of entire databases or tables for development, testing, or auditing purposes. Additionally, Snowflake provides the ability to recover data from a specific point in time using its "time travel" feature.
  • Security and compliance: Snowflake offers robust security features, including role-based access control, encryption, and comprehensive auditing capabilities. It complies with industry-standard security and compliance certifications.
  • Data integration and ETL: Snowflake provides connectors and integrations with various data integration tools, making it easy to ingest data from multiple sources. It also supports Extract, Transform, Load (ETL) processes.
  • SQL-Based querying: Snowflake uses a standard SQL interface, allowing users to write queries in a familiar language. It supports a wide range of SQL functions and features.
  • Data sharing and collaboration: Snowflake's data sharing capabilities allow organizations to securely share data with external partners, customers, or internal departments without the need for data movement.
  • Cost transparency and optimization: Snowflake provides detailed usage metrics and cost tracking, enabling organizations to monitor and optimize their cloud data warehouse costs.

Snowflake has gained popularity for its ability to handle massive amounts of data with ease, its scalability, and its focus on cloud-native architecture. It's widely used across industries for data analytics, business intelligence, machine learning, and more.

Methods to load data from SQL Server to Snowflake 

Method 1: using fivetran tool 

The process of loading data from SQL Server to Snowflake is made simpler by the powerful cloud-based data integration tool Fivetran. Fivetran helps organizations to seamlessly migrate and sync data, guaranteeing that it is available for analysis. It does this with a straightforward interface and automated procedures. This technique makes it possible for both technical and non-technical users to use it since it does not require human scripting or intricate data conversions.

To provide simple data extraction, Fivetran provides pre-built interfaces for a variety of data sources, including SQL Server. It effectively manages incremental updates, data format conversions, and schema changes while preserving the quality and integrity of the data during the transfer process. Furthermore, it has strong data transformation features that let users perform personalized changes on data before importing it into the data warehouse.

Organizations can save time and money by utilizing Fivetran to load data from SQL Server to Snowflake, allowing them to concentrate more on data analysis and decision-making than on the challenges of data integration. Fivetran gives companies the tools they need to unleash the full potential of their connection combinations, generate insightful data, and implement data-driven initiatives by using an automated and dependable data loading process.

Advantages of using fivetran 

Here are a few key advantages of using Fivetran to load data from SQL Server to Snowflake:

  • Seamless data integration: Fivetran provides pre-built connectors for various data sources, including SQL Server and data warehouses including Snowflake, eliminating the need for manual scripting or complex configurations. This simplifies the data integration process, saving time and effort.
  • Automated workflows: Workflows that are automated help to reliably and often sync data by automating the data loading procedure. It manages incremental updates, data format changes, and schema changes, minimizing manual intervention and preserving data integrity.
  • Data transformation capabilities: Users can apply unique transformations to the data before importing it into the data warehouse thanks to its strong data transformation capabilities. This makes it possible to clean, normalize, and enhance data, ensuring that it is prepared for analysis.
  • Monitoring and alerting: It offers tracking capabilities for alerting and monitoring the data integration process. It provides visibility into data loading metrics, error handling, and notifications for any problems that arise.
  • Data source flexibility: Different types of data sources are supported by Fivetran. Organizations can combine data from numerous sources into data warehouses like Snowflake because of its ability to connect to various databases, cloud services, and apps.
  • Time and resource savings: By automating the data loading process and eliminating the need for manual intervention, Fivetran saves valuable time and resources. This allows teams to focus on data analysis and deriving insights from the loaded data.

Method 2: using custom ETL scripts 

Loading data from SQL Server to Snowflake using custom ETL (Extract, Transform, Load) scripts involves a good amount of technical knowledge and several steps. Here are the steps involved to carry out the process:

Step 1: Setting up snowflake connection

  • Install the Snowflake ODBC driver or use a supported Snowflake client library.
  • Obtain the necessary connection details (e.g., account name, username, password, warehouse, database, schema, etc.) for Snowflake.


import snowflake.connector

# Define Snowflake connection parameters

conn = snowflake.connector.connect(








Step 2: Creating a custom ETL Script

  • Choose a programming language you're comfortable with (e.g., Python, Java, etc.).
  • Set up the necessary libraries or packages for your chosen language to interact with both SQL Server and Snowflake.

Step 3: Extracting data from SQL Server

  • Connect to the SQL Server database.
  • Write a SQL query to extract the data you need. You can use this query in your script to pull the data.

import pyodbc 

# Connect to SQL Server 

conn_str = 'DRIVER={SQL Server};SERVER=<server_name>;DATABASE=<database_name>;UID=<username>;PWD=<password>' conn_sql_server = pyodbc.connect(conn_str) 

# Define SQL query for extraction 

query = 'SELECT * FROM <table_name>' 

# Execute the query 

cursor = conn_sql_server.cursor() cursor.execute(query) 

# Fetch the results 

data = cursor.fetchall()

Step 4: Data transformation

Apply any required data transformations. This could include cleaning, filtering, joining, aggregating, or any other operations.

import pandas as pd

# Assuming 'data' is a list of tuples or a result 

set df = pd.DataFrame(data, columns=['column1', 'column2', ...]) 

# Apply transformations (e.g., filtering, aggregation, etc.) # Example: Filter rows where 'column1' is greater than 100 

transformed_data = df[df['column1'] > 100]

Step 5: Loading data into snowflake

  • Connect to Snowflake using the obtained connection details.
  • Use the Snowflake-specific libraries or drivers to interact with the Snowflake database.
  • Execute the necessary commands to load the data. This may include creating tables, defining schemas, and inserting data.


# Assuming 'transformed_data' is a pandas DataFrame

cursor_snowflake = conn.cursor()

# Create a Snowflake table (if it doesn't exist)

cursor_snowflake.execute('CREATE TABLE IF NOT EXISTS my_table (column1 STRING, column2 INT)')

# Insert data into Snowflake table

for index, row in transformed_data.iterrows():

    cursor_snowflake.execute("INSERT INTO my_table (column1, column2) VALUES (%s, %s)", (row['column1'], row['column2']))

# Commit the changes


Step 6: Error handling, scheduling, testing, deployment, and monitoring

  • Implement error handling to deal with potential issues during the ETL process. This could include connection failures, data format issues, etc.
  • Set up logging to keep track of the ETL process which will help in debugging and monitoring the issues easily.
  • Depending on your requirements, set up a schedule to run the ETL process at regular intervals. You can use tools like cron jobs (for Unix-based systems) or Task Scheduler (for Windows).
  • Thoroughly test your ETL script with different scenarios to ensure it handles all cases correctly.
  • Deploy your ETL script on the appropriate server or environment.
  • Set up monitoring for your ETL process. This can include alerts for successful completions as well as failures.
  • Regularly review and update your ETL script as needed to accommodate changes in data sources or destination schemas.

Keep in mind that while the above steps provide a general outline, the specific implementation details may vary based on your chosen programming language, libraries, tools, system and environment configurations. Additionally, it's important to handle security considerations such as credentials management and encryption while dealing with sensitive data or you can always opt for a low-code data replication solution like Fivetran.

Disadvantages of using ETL scripts 

Using custom ETL scripts for loading data from SQL Server to Snowflake has its advantages, but it also comes with potential disadvantages:

  • Complexity and maintenance: Custom scripts require more effort to develop, test, and maintain compared to using ETL tools or platforms with graphical interfaces. This complexity can increase over time as data sources or requirements change.
  • Limited scalability: Custom scripts may not scale as efficiently as specialized ETL tools. They may struggle to handle large volumes of data or complex transformations, potentially leading to performance issues.
  • Security Concerns: Handling credentials and sensitive information in scripts requires careful management to ensure security. Storing passwords directly in scripts can pose a security risk if not properly protected.
  • Error handling and recovery: Building robust error handling and recovery mechanisms can be complex. It's important to handle various types of errors (e.g., network issues, database timeouts, data format errors) to ensure the ETL process is reliable.
  • Limited monitoring and logging: Custom scripts may lack sophisticated monitoring and logging capabilities. Setting up comprehensive monitoring and logging may require additional development effort.
  • Lack of GUI for visualization: Unlike some ETL tools, custom scripts typically do not provide a graphical user interface for designing and visualizing the ETL process. This can make it harder to understand and debug the flow.
  • Platform dependencies: Custom scripts may be platform-dependent, meaning they may not work on all operating systems without modification. This could be a consideration if you need to run ETL on different environments.
  • Longer development time: Developing custom scripts may take longer compared to setting up ETL processes in a visual tool. This could be a concern if you have tight project deadlines.
  • Less community support: Custom scripts may have less available documentation and community support compared to widely-used ETL tools. This could make it harder to find solutions to specific issues.

It's important to carefully weigh these disadvantages against the specific requirements and constraints of your project. In some cases, custom scripts may be the best option, while in others, using a dedicated ETL tool might be more efficient and scalable.


To summarize, successfully loading data from SQL Server to Snowflake opens up a world of possibilities for organizations seeking to optimize their data analytics capabilities. By seamlessly migrating and transforming data from a traditional SQL Server environment to the modern, cloud-native platform of Snowflake, businesses can harness the power of scalable computing and robust analytics. This transition empowers them to make more informed decisions, gain deeper insights, and drive innovation across their operations. With a well-structured ETL process in place, organizations can confidently navigate the data landscape, ensuring that their information is not only secure and efficiently managed, but also readily available for transformative analysis. By embracing this integration, companies position themselves to thrive in today's data-driven landscape, making the most of their information assets to achieve strategic objectives.

Fivetran simplifies the data loading process from SQL Server to Snowflake by providing pre-built connectors, automated workflows, and data transformation capabilities. It streamlines the integration between any two platforms, allowing users to focus on analysis rather than integration complexities. To learn more about Fivetran, read What is Fivetran? | Blog. 

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