A Complete Comparison of PostgreSQL vs Microsoft SQL Server

Consider a switch from a commercial to an open source database. Discover the key differences and similarities between PostgreSQL and SQL Server.

PostgreSQL and SQL Server (or MSSQL) are widely used relational databases. Although they share several core traits, there are significant differences between them. This article provides a detailed rundown of the similarities and differences between PostgreSQL and SQL Server.

Among the most important distinctions is that PostgreSQL is open source, while SQL Server is owned and licensed by Microsoft. In addition, you will learn about the differences between the two systems regarding licensing and cost, ease of use, SQL syntax and compliance, data types, available features, performance, and security, among over 40 other topics covered in head-to-head comparisons.

It will benefit organizations thinking of switching from a commercial to an open source database but need more information on the possible trade-offs and advantages of the two systems. However, it is intended for anyone who is curious to learn more about relational databases.

PostgreSQL vs. MSSQL – Server Licensing Models

PostgreSQL

PostgreSQL is an open source database released under the PostgreSQL License, an Open Source Initiative Approved License. The use of PostgreSQL for any purpose, including commercial, is free. Under the PostgreSQL Global Development Group, PostgreSQL is available as free and open source software in perpetuity.

SQL Server

Microsoft SQL Server is available through a commercial license and can be licensed on a per-core or server and client access level (CAL) model. MSSQL is offered in two main editions, Enterprise Edition and Standard Edition, to meet organizations' and individuals' performance and price requirements. Licensing costs range from $3,586 for the Standard Edition to $13,748 for the Enterprise Edition (for two cores); the server and CAL model run $899 for the server plus $209 per user. A free version is available to students and developers for building and testing.

PostgreSQL vs. MSSQL – Release Updates

PostgreSQL

PostgreSQL was created in 1986 at the University of California, Berkeley, and first released in 1989. It has undergone several significant updates since then, and the project still maintains regular releases under an open source license. The current version of Postgres is version 13,  released in October 2019 and has had regular minor releases since then. Previous significant versions are supported for five years after their initial release.

SQL Server

Microsoft developed SQL Server and first released it in 1989, and new releases occur regularly. The current version, Microsoft SQL Server 2019, was released in November 2019. Previous versions continue to receive support from SQL Server 2012 onward. Recent versions include extended support for 10 years, with an optional premium assurance paid extension for up to 16 years.

PostgreSQL vs. MSSQL – Which Server Is Easier to Use?

PostgreSQL

PostgreSQL is an advanced object-relational database management system that uses Structured Query Language (SQL) and its procedural language, PL/pgSQL. PostgreSQL is easy to use and has a whole stack of RDBMS database features and capabilities for handling data. You can easily install it on Linux environments.

SQL Server

SQL Server is a Relational Database Management System (RDBM) developed and operated by Microsoft. It uses a variant of Structured Query Language (SQL) called T-SQL (for Transact-SQL). It can run on Linux operating systems with Kubernetes support or on Windows. Users describe it as easy to use and reliable, with strong .NET compatibility.

PostgreSQL vs. MSSQL – Server Syntax

PostgreSQL vs. SQL Server Syntax Comparison Table

PostgreSQL vs. MSSQL – Data Types

PostgreSQL vs. SQL Server Data Types Comparison Table

PostgreSQL vs. MSSQL – Geographic Data

PostgreSQL

PostgreSQL does not have a native data type for geographic data. The open source PostGIS resource offers support for geographic objects.

SQL Server

SQL Server has the geography data type for storing geographic spatial data.

PostgreSQL vs. MSSQL – Case Sensitivity

PostgreSQL

PostgreSQL is case-sensitive for evaluating strings. The LOWER() function allows users to convert strings to all lowercase for evaluation purposes (there is also a similar UPPER() function). By default, PostgreSQL converts table and column names to lowercase unless you place those names in quotes. The context module provides a case-insensitive string data type context for comparing values.

SQL Server

SQL Server is case insensitive by default. Adjusting the SQL Server’s collation settings can change the case sensitivity. Set the collation settings for case sensitivity at the database or column level.

PostgreSQL vs. MSSQL – Index Types

PostgreSQL

PostgreSQL offers several options for index types, including B-tree, hash, Generalized Search Tree (GiST), Space Partitioned GiST, Generalized Inverted Index (GIN), and Block Range Index (BRIN). In addition, it supports expression indexes (indexes created with an expression or function rather than a column value) and partial indexes (indexes of part of a table).

SQL Server

SQL Server offers clustered and nonclustered indexes. Clustered indexes sort and store data rows in the table or view based on fundamental values (columns in the index definition). A table can have only one clustered index. Nonclustered indexes are stored separately from table data, and each key value entry has a pointer to the data. MSSQL automatically creates these indexes when you define PRIMARY KEY and UNIQUE constraints on table columns. The UNIQUE constraint creates a nonclustered index, while the PRIMARY KEY creates a clustered index unless one already exists.

PostgreSQL vs. MSSQL – Replication

PostgreSQL

PostgreSQL has Primary-Secondary replication. Replication can be synchronous or asynchronous. Asynchronous replication uses write-ahead logs (WALs) to share changes with the replica nodes. Streaming replication updates standby servers more immediately by streaming the WALs as they are created rather than waiting for the file to be filled.

Logical replication follows a publish and subscribe model, where changes are based on the data's replication identity (a primary key) rather than its physical location, hence the name "logical replication." Physical replication deals with files and directories without regard for the contents within those physical locations. PostgreSQL does not natively offer multi-master replication, but some third-party tools offer multi-master replication solutions.

SQL Server

SQL Server replication duplicates data from a Publisher server to a Subscriber and offers three types of replication:

1. Transactional replication for server-to-server environments, where changes are delivered from the publisher to the subscriber as they occur.
2. Merge replication for server-to-client environments or in situations where conflicts might occur, where data can be changed and tracked on either the publisher or subscriber and later synchronized.
3. Snapshot replication is when data is updated infrequently or does not need to be changed incrementally, where data is duplicated precisely as it appears at a specific moment.

Replication in SQL Server can be a synchronous commit or asynchronous commit. The Enterprise edition offers peer-to-peer replication as an alternative solution to multi-master replication.

PostgreSQL vs. MSSQL – Clustering

PostgreSQL

PostgreSQL allows clusters of servers but does not natively support multi-master or active/active clusters. Tools such as repmgr allow for easy maintenance of PostgreSQL clusters.

SQL Server

SQL Server offers Windows Server Failover Clustering, which can be configured for both active/passive and active/active nodes. The Standard edition only supports two nodes for clusters; additional nodes require an upgrade to the Enterprise edition.

PostgreSQL vs. MSSQL – High Availability

PostgreSQL

PostgreSQL offers several solutions to ensure high availability for users, including shared disk failover, write-ahead log shipping, data partitioning and multiple replication methods. Tools like EDB Postgres Failover Manager provide automatic failover to ensure high availability by monitoring and identifying database failure.

SQL Server

SQL Server includes several high-availability tools in its various editions. These include replication, log shipping, and failover clusters. Its Always On availability groups, offered with the Enterprise edition, provide automatic failover when certain conditions are met.

PostgreSQL vs. MSSQL – “Views”

PostgreSQL

PostgreSQL supports views – virtual tables that do not store data themselves. Updatable views are supported, but updates do not occur automatically unless they meet the following conditions:

1. The query of that view must have precisely one section in the FROM clause, which can be a table or another updatable view.
2. The selection list must not contain any window function, aggregate function, or set-returning function.
3. The query must not contain one of the following clauses at the top level: HAVING, LIMIT, DISTINCT, WITH, INTERSECT, EXCEPT, OFFSET, AND LIMIT.

Views created with simple queries can be updated; ones made with complex queries cannot, but complex views can be updated using rules. Materialized views are also supported and the data in materialized views can be updated using the REFRESH MATERIALIZED VIEW statement.

SQL Server

SQL Server views can be used to restrict user access to data for security purposes. Both user-defined and system-defined views are supported. Views can be automatically updated using triggers. The data in a view can be updated when the modifications are made to a column from a single underlying base table and are referenced directly. Materialized views are known in SQL Server as Indexed Views; unlike materialized views in other relational databases, indexed views are synched to the underlying data and are thus updated automatically.

PostgreSQL vs. MSSQL – Triggers

PostgreSQL

PostgreSQL has advanced triggers. Supported triggering events include AFTER, BEFORE, and INSTEAD OF, which apply to INSERT, UPDATE, and DELETE events. When a trigger fires, it can execute complex SQL statements using functions. PostgreSQL can execute this dynamically.

SQL Server

SQL Server offers triggers for different types of database events:

1. DML Triggers: for a data manipulation language (DML) specific event, such as inserting, updating, or deleting records. These triggers fire on events irrespective of the number of rows affected.
2. DDL Triggers: for data definition language (DDL) events, such as CREATE, DROP, or ALTER statements. These are useful for preventing or auditing changes to the database schema.

Logon Triggers allow you to respond to user session establishment events. These triggers fire after successful authentication and before establishing the user session. They are helpful for auditing and controlling login activity.

PostgreSQL vs. MSSQL – Stored Procedures

PostgreSQL

PostgreSQL supports stored procedures as user-defined functions with a RETURN VOID clause. SQL Server supports stored procedures written in various languages alongside standard SQL syntax.

SQL Server

SQL Server supports stored procedures for languages supported by Microsoft .NET framework (common runtime languages or CLR, like VB, C#, or Python).

PostgreSQL vs. MSSQL – Query

PostgreSQL

PostgreSQL offers the PL/pgSQL procedural programming language. Additional functionalities to standard SQL in PostgreSQL include:

• Advanced types and user-defined types.
• Extensions and custom modules.
• JSON support.
• Further options for triggers and other functionality.

SQL Server

SQL Server uses T-SQL, which has a similar query syntax to standard SQL. T-SQL includes additional support for strings and data processing, local variables, and procedural programming.

PostgreSQL vs. MSSQL – Full-Text Search

PostgreSQL

PostgreSQL offers advanced functionality for full-text search. It uses full-text indexing and dictionaries for faster searches. PostgreSQL stores pre-processed text documents as vector data types and processed queries as their dedicated type. Pre-processing parses text documents into linguistic units known as lexemes, which allows you to find case-insensitive variants of a word.

SQL Server

SQL Server offers full-text search as an optional component. Full-text indexes enable searches based on specific language rules. Searches are performed on columns or text data types (including char, varchar, nchar, nvarchar, text, ntext, image, xml, or varbinary(max) and FILESTREAM) using the T-SQL commands CONTAINS to match words and phrases and FREETEXT to match meaning. Thesaurus files can be used to help find synonyms of search terms. Full-text searches in SQL Server are not case sensitive.

PostgreSQL vs. MSSQL – Regular Expressions

PostgreSQL

PostgreSQL has three methods for evaluating regular expressions: LIKE, SIMILAR TO, and POSIX regular expressions.

SQL Server

SQL Server does not natively support regular expression evaluation; similar but limited results can be achieved using the T-SQL functions LIKE, SUBSTRING, and PATINDEX.

PostgreSQL vs. MSSQL – Partitioning

PostgreSQL

PostgreSQL offers built-in support for range, list, and hash partitioning. Range partitioning groups a table into ranges defined by a partition key column or set of columns – for example, by date range. List partitioning breaks a table into groups by explicitly listing predefined fundamental values in each partition.

EDB Postgres Advanced Server also supports Interval Partitioning, which automatically creates the interval partitions as data arrives without causing deadlocks.

SQL Server

SQL Server supports table and index partitioning. The data is partitioned horizontally and maps groups of rows into individual partitions. All partitions of a single index or table must reside in the same database and the table or index is treated as a single entity for queries and updates.

PostgreSQL vs. MSSQL – Table Scalability

PostgreSQL

PostgreSQL has a handful of indexing and two types of partitioning options to improve data operations and query performance on a scalable table. Table partitions and Indexes can be placed in separate tablespaces on different disk file systems, significantly improving table scalability. Postgres does not support horizontal table partitioning, but several commercially developed products are available.

SQL Server

SQL Server contains scalability enhancements to the on-disk storage for memory-optimized tables. The current versions offer multiple concurrent threads to persist memory-optimized tables, multithreaded recovery and merge operations, and dynamic management views. Scaling in SQL Server can be easily achieved through sharding.

PostgreSQL vs. MSSQL – Table Statements

PostgreSQL vs. MSSQL – Compliance

PostgreSQL

PostgreSQL is an object-relational database management system (ORDBMS) emphasizing extensibility and standards compliance. It is ACID-compliant. EDB Postgres Advanced Server is also HIPAA, GDPR, and PCI compliant.

SQL Server

SQL Server is a relational database management system (RDBMS) emphasizing security and performance. It is ACID-compliant.

PostgreSQL vs. MSSQL – Columns

PostgreSQL

PostgreSQL introduced a new constraint feature in version 10 called GENERATED AS IDENTITY. This SQL-compliant variant of the SERIAL column allows you to assign a unique value to an identity column automatically.

For a SERIAL column to have a unique constraint or be a primary key, it must now be specified, just like other data types. Unique identifier columns are created using the data types smallserial, serial, and bigserial, similar to auto-increment features in different databases.

SQL Server

SQL Server's identity column property creates an identity column for a table to generate critical values for rows. Two values are specified when it is made: seed (initial value for the first row) and increment (amount to increase value over the previous row). By default, both the seed and incremental values are 1. Each table can only contain one identity column. The uniqueness of the values is not guaranteed unless PRIMARY KEY or UNIQUE constraints are imposed.

PostgreSQL vs. MSSQL – Computed Column

PostgreSQL

PostgreSQL uses the term generated columns for computed columns. This feature was introduced with version 12. Generated columns can be physically stored when marked STORED; otherwise, they are not stored and are known as virtual.

CREATE TABLE table (
…,    
computed_column GENERATED ALWAYS AS (expression) STORED
);

Generated columns cannot have an identity definition or be part of a partition key; they can only reference the current row and cannot use subqueries. Values cannot be specified using INSERT or UPDATE, but the keyword DEFAULT is accepted.

SQL Server

SQL Server computed columns are not physically stored in a table unless marked with the PERSISTED property; the column can only be persisted when the value is deterministic or always returns the same result.

ALTER TABLE table
ADD computed_column AS expression [PERSISTED]; 

If the computed column is deterministic and an acceptable data type, it can be used as a PRIMARY KEY or index but not as a DEFAULT or FOREIGN KEY constraint. Values cannot be specified using INSERT or UPDATE.

PostgreSQL vs. MSSQL – Deleting Table Data

You can delete data from a table in PostgreSQL using the DELETE statement:

DELETE FROM table
WHERE condition;

The DELETE FROM clause specifies the table and the rows to delete are specified by using the condition in the WHERE clause. The WHERE clause is optional, but if you omit it, the statement will delete all rows in the table.

The DELETE statement removes rows from a table in SQL SERVER:

DELETE FROM table
WHERE condition;

The name of the table from which the rows are to be deleted is specified in the FROM clause, and the rows to delete are specified by the condition in the WHERE clause. The WHERE clause is optional, but if you skip it, all rows from the table will be removed.

You can specify the number or percent of random rows that will be deleted by using the TOP clause.

DELETE TOP 10 FROM table;

This statement removes 10 random rows from the table. Because rows are stored in unspecified order, we do not know which 10 rows will be deleted. Similarly, you can delete the 10 percent of random rows:

DELETE TOP 10 PERCENT FROM table;

PostgreSQL vs. MSSQL – Integers

PostgreSQL

There are three kinds of integers in PostgreSQL:
SMALLINT (small integer, a 2-byte type with a range from -32,768 to 32,767)
INT (integer, a 4-byte type with a range from -2,147,483,648 to 2,147,483,647)
BIGINT (a large-range integer: -9223372036854775808 to 9223372036854775807)

SQL Server

SQL SERVER supports standard SQL integer types BIGINT, INT, SMALLINT, and TINYINT. The range and storage size of each type is as follows:

PostgreSQL vs. SQL Server Integers Comparison Table

PostgreSQL vs. MSSQL – Boolean Types

PostgreSQL

The PostgreSQL Boolean data type can have three states:

1. TRUE
2. FALSE
3. NULL

SQL Server

The BIT data type in SQL SERVER represents true/false boolean data. A BIT field's value is either 1, 0, or null.

PostgreSQL vs. MSSQL – NoSQL Capabilities

PostgreSQL

Like many other relational databases, PostgreSQL has added support for JSON data, the most common format for semi-structured data stored in NoSQL systems. However, because SQL is the only way to interact with a PostgreSQL database, it should not be considered NoSQL.

SQL Server

SQL Server has native JSON functions that enable you to parse JSON documents using standard SQL language. You can store JSON documents in an SQL Server and query JSON data as in a NoSQL database. Still, because SQL Server is an SQL database, it should not be considered NoSQL.

PostgreSQL vs. MSSQL – Security

PostgreSQL

PostgreSQL supports SSL (Secure Sockets Layer) connections to encrypt client-server communications. You can enable SSL by setting the SSL parameter in the postgresql.conf file. To meet enterprise needs, the EDB Postgres Advanced Server includes:

1. Additional built-in auditing features that capture detailed data
2. Integrated password policy management capabilities
3. Data redaction

SQL Server

SQL Server offers a range of features and functions to prevent security threats because each application has unique security needs. The SQL Server security framework manages access to securable entities through authentication and authorization. SQL Server supports a hierarchy of encryption options and supports TLS (transport layer security) for encrypting network traffic.

PostgreSQL vs. MSSQL – Analytical Functions

PostgreSQL

PostgreSQL supports various analytical functions, which perform aggregation on a set of rows. There are two types of analytical functions: window functions and aggregate functions. Aggregate functions perform aggregation and return a single aggregate value for a set of rows (like sum, avg, min, or max). Window functions return a single aggregate value for each of the rows.

PostgreSQL supports the following window functions:

SQL Server

SQL Server's analytic functions empower you to calculate moving averages, running totals, percentages, or top-N results directly within a group.

SQL Server supports the following analytic functions:

PostgreSQL vs. MSSQL – Dynamic Actions

PostgreSQL

PostgreSQL prioritizes security and predictability by avoiding dynamic actions. Achieve most similar operations using well-defined SELECT statements.

SQL Server

For enhanced security, SQL Server restricts dynamic actions. Achieve similar functionalities through well-defined stored procedures.

PostgreSQL vs. MSSQL – Administration and GUI Tools

PostgreSQL

PostgreSQL can be administered through a GUI using Oracle’s SQL Developer, pgAdmin, OmniDB, DBeaver, and Postgres Enterprise Manager. Other GUI tools for monitoring health and performance include Nagios, Zabbix, Cacti, and EDB Postgres. SQLECTRON is a cross-platform option that is free and open source; it is compatible with several SQL databases, including SQL Server.

SQL Server

SQL Server can be administered through a GUI on Windows using SQL Server Management Studio (SSMS), which is free. SQL Operations Studio is a free, open source, cross-platform GUI for Mac. SQLECTRON is a free, open source, cross-platform option compatible with several SQL databases, including PostgreSQL.

PostgreSQL vs. MSSQL – Performance

PostgreSQL

PostgreSQL offers speed and performance across data sets of all sizes and it regularly outperforms other databases in both online transaction processing (OLTP) and online analytical processing (OLAP) speeds. It offers multi-version concurrency control (MVCC), processing multiple transactions simultaneously, with fewer deadlocks than SQL Server. PostgreSQL offers many tools and parameters that allow users to monitor and optimize database performance.

SQL Server

SQL Server prides itself on the speed of its analytical and transaction processing. However, because the SQL Server user agreement prohibits the publication of benchmark testing without Microsoft’s prior written approval, head-to-head comparisons with other database systems are rare. Among the features SQL Server highlights for optimizing performance and speed is its In-Memory OLTP, which takes advantage of in-memory data tables that perform better than writing directly to disk. The SQL Server Standard edition has some performance limitations for memory, partitioning, indexing, and other functionalities that require upgrading to the Enterprise version.

PostgreSQL vs. MSSQL – Concurrency

PostgreSQL

PostgreSQL has a well-developed multi-version concurrency control (MVCC) that handles multiple procedures simultaneously. MVCC provides snapshots of database info to avoid showing inconsistencies caused by simultaneous transactions or the locking of data that occurs in other database systems. It uses Serializable Snapshot Isolation (SSI) to guarantee transaction isolation.

SQL Server

SQL Server has a less fully developed multi-version concurrency control system and, by default, relies on data locking to prevent errors from simultaneous transactions. To improve performance, it implements optimistic concurrency. This approach skips row locking and instead verifies any changes against a cached version, assuming conflicts are rare.

PostgreSQL vs. MSSQL – Adoption

PostgreSQL

PostgreSQL is the world's most advanced open source database. Businesses across the globe are using PostgreSQL for mission-critical workloads. The PostgreSQL community and a few companies, such as EnterpriseDB and 2ndQuadrant, are ensuring that PostgreSQL adoption continues to expand globally.

SQL Server

SQL Server is popular with enterprises that rely on Microsoft products. It saw an increase in market share over the past two decades as Microsoft pushed it with its Windows Servers. However, with more and more enterprises shifting to open source in recent years, the popularity curve of SQL servers is becoming flatter and flatter.

PostgreSQL vs. MSSQL – Environment and Stack

PostgreSQL

PostgreSQL is popular with the LAPP stack (Linux, Apache, PostgreSQL, and PHP/Python. The LAPP stack is growing in popularity; large-platform service providers like Amazon and VMware provide services with readily installed LAPP stack modules.

SQL Server

SQL Server is a popular component of the Microsoft stack. It comprises Microsoft technologies like Microsoft WPF, ASP.NET, SharePoint, and Office 365.

PostgreSQL vs. MSSQL – Scheduling Tasks

PostgreSQL

PostgreSQL doesn’t provide a built-in job scheduler like other SQL databases do. Recurring tasks require external tools like pgAgent, cron, or pg_cron on Linux, and Task Scheduler or  SQLBackupAndFTP on Windows.

SQL Server

The SQL Server Management Studio schedules tasks in the SQL Server.

PostgreSQL vs. MSSQL – Data Redaction

PostgreSQL

PostgreSQL does not support data redaction to limit the display of sensitive data for specific users. Enterprises looking for data redaction features to add more security can use EDB Postgres Advanced Server, an Oracle-compatible fork of PostgreSQL.

SQL Server

SQL Server offers dynamic data masking (DDM). DDM limits sensitive data exposure by hiding it from users without the proper privileges. It complements other SQL Server security features like auditing, encryption, and row-level security.

PostgreSQL vs. MSSQL – Limitations

PostgreSQL

In addition to SQL and PL/pgSQL, PostgreSQL supports the procedural languages PL/Tcl, PL/Perl, and PL/Python in its distribution and supports the external procedural languages PL/Java, PL/Lua, PL/R, PL/sh (Unix shell), and PL/JavaScript. It also supports user-defined functions in C languages. It runs on various server operating systems, including Linux, Mac, Windows, BSD, and Solaris. It is easily deployed using Docker containers or Kubernetes.

SQL Server

In addition to T-SQL, SQL Server supports languages compatible with the Microsoft .NET framework, including C#, Java, PHP, and Python. SQL Server must run on Linux or Windows operating systems. It can be deployed on Docker containers and Kubernetes with Microsoft’s Azure Kubernetes Services.

PostgreSQL vs. MSSQL – Access Methods

PostgreSQL

PostgreSQL is compatible with the following access methods, protocols, and APIs for accessing its data: ADO.NET, JDBC, ODBC, and the native C library. It also supports a streaming API for binary large objects (BLOBs).

SQL Server

SQL Server is compatible with the following access methods, protocols, and APIs for accessing its data: ADO.NET, JDBC, ODBC, OLE DB, and TDS.

PostgreSQL vs. MSSQL – Bulk Collect and Binds

PostgreSQL vs. MSSQL – Synonyms

SQL Server supports synonyms. Synonyms provide a layer of abstraction that protects a client application from changes made to base objects. A synonym belongs to a schema; like other objects in a schema, its name must be unique. Binding is by name only; if a base object is modified, dropped, or replaced, the missing reference will only be found at run-time. PostgreSQL does not support synonyms.