Easy Migration: SQL Server to PostgreSQL, MSSQL to Postgres

Migrating from SQL Server to PostgreSQL is a complex and critical task, but with the right planning and tools, the process can be made relatively easy. Using pgloader is a powerful and flexible option, especially for large, complex databases. By properly configuring migration files, you can customize the migration process to meet your specific needs and ensure the security and accuracy of your data.

SQL Server to PostgreSQL Migration tool



Powerful command line tool that supports migration to PostgreSQL from multiple source databases, including SQL Server.

 Microsoft Data Migration Assistant (DMA)

Microsoft Data Migration Assistant (DMA)

A free tool provided by Microsoft that supports evaluating and performing database migrations.



Available in open source and commercial versions, with a graphical interface and support for multiple data sources and targets.



Open source tool that supports data replication and migration between multiple database systems.



Data documentation tools that also provide migration support and evaluation capabilities.



Database migration tool for developers, supporting version control and script execution.

How to Migrate SQL Server to PostgreSQL?

During the migration of SQL Server to PostgreSQL, carefully evaluate the differences between the two database systems, including compatibility of data types, functions, and stored procedures. Choose an appropriate migration tool, such as pgloader, to simplify the task of data migration and structural transformation. At the same time, be aware of differences between SQL syntax and features that may require you to manually adjust the code for some stored procedures or triggers.
The success of migration directly affects the stability of the database and the normal running of the application in the production environment. Therefore, before performing the migration, it is important to conduct thorough testing in a test environment to verify data consistency and application stability. Back up your data and have a rollback plan in place so that it can be restored quickly if something goes wrong during the migration.

Step 1: Install SQL Server to PostgreSQL Migration Tool

There are many tools that support SQL server to PostgreSQL migration tool, and we chose pgloader for the demo.
Pgloader is a powerful tool for migrating data from different database systems to PostgreSQL. It can handle data type mapping, structural transformation, and data loading between different databases, and provides flexible configuration options.

Update the package list:

sudo apt-get update

Install pgloader:

sudo apt-get install pgloader

Step 2: Export SQL Server Data

Use tools provided by SQL Server, such as BCP and SSIS, to export data:

bcp "SELECT * FROM YourTable" queryout data.txt -S YourServer -U YourUser -P YourPassword -c -t 

Step 3: Prepare the Pgloader Configuration File

Create a configuration file, such as migrate.load, that specifies the migration rules for SQL Server to PostgreSQL:

FROM mssql+sqlalchemy://username:password@server:port/database
INTO postgresql://username:password@localhost/my_postgres_db

WITH include no drop, create tables, create indexes, reset sequences,
data only

SET work_mem to '16MB',
maintenance_work_mem to '512 MB';

ALTER SCHEMA 'dbo' RENAME TO 'public';

Step 4: Perform the Pgloader Migration

Run the following command in the terminal:

pgloader migrate.load

What is Microsoft SQL Server?

Microsoft SQL Server is a relational database management system (RDBMS) developed by Microsoft Corporation. As an RDBMS, SQL Server is designed to store, retrieve, and manage structured data efficiently. It provides a robust and scalable platform for organizations to organize and manipulate data in a relational format.

SQL Server uses the Structured Query Language (SQL) as its query language. SQL enables users to perform various operations on the database, including querying data, inserting new records, updating existing records, and deleting records. It provides a standardized way to interact with the database and retrieve information based on specific criteria.

SQL Server offers advanced features such as security mechanisms to control access to data, integration services for data integration and transformation, analysis services for multidimensional data modeling, and reporting services for creating and managing reports. With its scalability, reliability, and integration capabilities, Microsoft SQL Server is widely used in enterprise environments to manage and maintain databases, support critical applications, and facilitate business intelligence and analytics. It is crucial in handling data-related tasks and providing a stable foundation for various software applications across diverse industries.

What is PostgreSQL?

PostgreSQL is an open-source object-relational database management system (ORDBMS) known for its extensibility, robustness, and adherence to SQL standards. It provides a platform for efficiently managing and handling structured data.

PostgreSQL follows the relational data model, organizing data into tables with rows and columns. It offers advanced features, including extensibility, support for custom data types and operators, and compliance with SQL standards. PostgreSQL enforces data integrity through constraints, supports advanced data types such as arrays and JSON, and implements concurrency control mechanisms like multi-version concurrency control (MVCC).

With support for transactions, indexing, optimization, and scalability, PostgreSQL is widely used across various applications and industries. Its open-source nature fosters a vibrant community of developers and users, contributing to ongoing development, support, and knowledge-sharing. PostgreSQL is a popular choice for projects of different scales, from small applications to large-scale enterprise solutions.

SQL Server vs PostgreSQL

Features PostgreSQL Traditional SQL Databases
Developed By PostgreSQL Global Development Group Microsoft
Open Source and Free YesMay have commercial licenses
Data Type Support Diverse, including arrays, JSON, XML, etc. Relatively traditional data type support
Extensibility Advanced, supports custom functions and pluginsMay be more limited
Performance OptimizationRobust performance optimization tools and settings Performance optimization varies by database
Concurrency Control MVCC (Multi-Version Concurrency Control) support Relies on traditional locking mechanisms
Spatial Features Rich support for spatial data Depends on the database
Integrity Constraints Supports various constraint types, including CHECK and FOREIGN KEY Typically supports basic integrity constraints
Triggers and Stored Procedures Supports complex triggers and stored procedures Depends on the database
Integration Services SQL Server Integration Services (SSIS) for ETL Supports ETL through external tools, native tools, and extensions

Why Choose PostgreSQL?

check_circleOpen Source and Free
PostgreSQL is an open-source project and is free to use. In contrast, Microsoft SQL Server is a commercial database management system that requires the purchase of a license.
check_circleStandard Compatibility
PostgreSQL follows the SQL standard and emphasizes standard compatibility. Microsoft SQL Server also supports the SQL standard, but in some cases there may be some Microsoft-specific extensions.
check_circleCommunity Support
PostgreSQL has a large global community with extensive documentation, support, and plugins. The activity of this community helps to solve problems in a timely manner and move the system forward.
PostgreSQL allows users to write custom functions, operators, and extensions, providing greater freedom. SQL Server, of course, also provides an extension mechanism, but PostgreSQL may be more flexible in this regard.
check_circleMulti-version Concurrency Control
PostgreSQL's Multi-version concurrency Control (MVCC) mechanism allows multiple transactions to be executed concurrently without causing data inconsistency. SQL Server also has concurrency control mechanisms, but the specific implementation and performance may vary from version to version.
check_circleCross-Language Support
PostgreSQL supports stored procedures and functions in a variety of programming languages, including PL/pgSQL, PL/Python, PL/Java, and more. This makes it more flexible to implement business logic in the database. SQL Server mainly uses Transact-SQL (T-SQL), although some extension languages are also supported, but can be relatively flexible.

Select Cloud Clusters for SQL Server to PostgreSQL

When this is done, it is also necessary to migrate database structures, stored procedures, triggers, etc., perform performance optimization, and update application connections. Overall, migrating SQL Server to PostgreSQL is a complex task involving multiple steps and technical considerations. If you're looking for an easier, faster way to migrate SQL to PostgreSQL, consider Cloud Clusters' PostgreSQL hosting service.

Selecting Cloud Clusters as your strategic partner is a savvy choice. Cloud Clusters not only has a deep understanding of the needs of database and application modernization but also has extensive technical expertise in migration. You can have a successful software modernization project by choosing Cloud Clusters to provide a professional PostgreSQL hosting service. Cloud Clusters provides technical support during the migration process and works closely with your team to ensure that the entire process causes minimal disruption to your business operations. By choosing Cloud Clusters, you get a partner who is committed to excellence and success and will help you realize your vision of software modernization to bring an even greater competitive advantage to your business.