Understanding PostgreSQL for Those with SQL Server Experience
Many people who use SQL Server look at PostgreSQL. This happens when companies want to save money or need more flexibility. Sometimes, they need to work with data like JSON or shapes. People switch because PostgreSQL is open-source and has strong security. It can also handle big jobs well. Knowing SQL Server helps a lot. But PostgreSQL has special features and ways to connect. Learning more about it is helpful.
Key Takeaways
PostgreSQL is a strong, open-source database. It gives you lots of choices and keeps data safe. It does not cost as much as SQL Server.
PostgreSQL has its own way of working. It uses different processes for each connection. It has cool features like JSON data, custom types, and many procedural languages.
Indexing and partitioning in PostgreSQL help make queries faster. They help manage big data well. This is good for large tables and special data types.
PostgreSQL’s MVCC concurrency model lets many people use data at once. They can read and write without stopping each other. This helps the database work better when lots of people use it.
Migration tools and cloud services like Azure Database for PostgreSQL help companies switch from SQL Server easily. This means less downtime and lower costs.
PostgreSQL vs SQL Server
Architecture
PostgreSQL and SQL Server both use a client-server setup. Users connect to the database with a client. The server stores and works with the data. Each system manages connections and memory in its own way.
Both systems have advanced SQL features. They support concurrency control and indexing. PostgreSQL uses MVCC to handle transactions. SQL Server also has strong concurrency tools. Both can use many data types, like arrays and spatial types.
Tip: Both databases can keep running if something fails. They also let you copy data for safety.
Features
PostgreSQL and SQL Server have many features that help businesses. Both follow ACID rules. They can run complex queries. They use different ways to index data. They also have tools for backup and restore. High availability is supported too.
PostgreSQL has some special features:
It can use JSON data and functions.
It supports table inheritance for tree-like data.
Foreign Data Wrappers let it reach outside data.
It has advanced indexes like BRIN and partial indexes.
You can write stored procedures in many languages.
It allows custom data types and has many extensions.
SQL Server works well with Microsoft tools. It has Transparent Data Encryption. It also has Always On Availability Groups.
Licensing
Licensing is very different for PostgreSQL and SQL Server. PostgreSQL is open-source. You do not pay for a license. You can use, change, and share PostgreSQL. SQL Server is commercial. You must pay for each core, server, or CAL.
SQL Server has rules like minimum core licensing. You may pay more for CALs. PostgreSQL does not have these limits. Companies using PostgreSQL do not get stuck with one vendor. They can control their spending.
Note: PostgreSQL’s open-source license lets companies be flexible and creative.
Key PostgreSQL Concepts
Indexing
Indexing helps databases find things fast. Both PostgreSQL and SQL Server use B-Tree indexes for most searches. PostgreSQL does not use clustered indexes. It keeps tables as unordered heaps. Indexes use pointers to find data. This makes index upkeep easier. It does not keep rows in order. PostgreSQL added B-Tree deduplication in version 13. This stores repeated values once per index page. It makes indexes smaller and faster. This helps when many rows have the same value. SQL Server keeps each index entry by itself. This can use more space.
PostgreSQL has special index types like BRIN, SP-GiST, and GiST. These help with big tables or shapes. SQL Server has XML and columnstore indexes. PostgreSQL can use these with extensions. Both let you make partial indexes. SQL Server calls them filtered indexes. For full-text search, PostgreSQL uses GIN and GiST indexes. SQL Server uses inverted indexes. The table below compares index types:
Tip: Pick the right index type for your data and searches. PostgreSQL gives more choices for special data.
Partitioning
Partitioning splits big tables into smaller parts called partitions. Both PostgreSQL and SQL Server use partitioning to make things faster and easier to manage. PostgreSQL supports RANGE, LIST, and HASH partitioning. RANGE splits data by value ranges. LIST uses certain values. HASH spreads data out evenly. Declarative partitioning started in PostgreSQL version 10. It makes setup and management easier.
The table below compares partitioning features:
Partitioning helps queries go faster if the partition key matches the search. It works best for huge tables, over 250 GB. For small tables, good indexing is enough. Partitioning can make inserts quicker. New data goes to the newest partition. But it adds extra steps and needs planning.
Partitioning makes searches faster with the right key.
Too many partitions can be hard to manage.
Updates across partitions can slow things down.
Data Types
PostgreSQL and SQL Server have many data types. Some are special to each system. PostgreSQL has a true BOOLEAN type, native arrays, and a UUID type. It also supports JSON and JSONB for storing and searching JSON data. SQL Server uses BIT for boolean values, UNIQUEIDENTIFIER for UUIDs, and keeps JSON as NVARCHAR.
PostgreSQL's JSONB type lets you search and update inside JSON documents quickly. It also supports arrays. Arrays let you keep lists of values in one column. These features make PostgreSQL strong for new apps.
Concurrency
Concurrency means how well a database works with many users at once. PostgreSQL uses Multi-Version Concurrency Control (MVCC). MVCC lets many versions of data exist together. Readers do not block writers. Writers do not block readers. Each transaction sees the data as it was when it started. This makes things faster and reduces waiting.
SQL Server uses locking. It puts locks on rows, pages, or tables to keep data safe. This can cause blocking if many users change the same data. SQL Server also has snapshot isolation. It is like MVCC but uses more storage.
Note: MVCC in PostgreSQL works well for lots of reading and many users. It needs regular cleanup to remove old data.
Backup
Backup keeps data safe. SQL Server has built-in backup tools. You can run backups with T-SQL or SQL Server Management Studio. It has compression, encryption, and point-in-time recovery. SQL Server supports full, differential, and transaction log backups.
PostgreSQL uses outside tools for backup. The main tool is pg_dump. It makes logical backups. For big databases, you can use physical backups or continuous archiving with Write-Ahead Logging (WAL). This lets you do point-in-time recovery by replaying WAL logs after a base backup. PostgreSQL backups need more manual steps. They give you more choices.
Tip: PostgreSQL can do point-in-time recovery with WAL logs. This is powerful but needs careful setup and watching.
Migration and Integration
Migration Tools
Many companies use migration tools to switch from SQL Server to PostgreSQL. These tools help move data, tables, and code. Some popular tools are AWS Schema Conversion Tool, Database Migration Service, DBConvert, and Ispirer Toolkit. Each tool is good at different things. For example, one online store used AWS SCT, DMS, and DBConvert together. They moved 750GB of data and 300 tables. The move kept the system up 99.5% of the time. It finished in six hours. After moving, the company’s JSON queries ran 40% faster. They also saved 70% on license costs. Ispirer Toolkit can do most migrations by itself. It works ten times faster than doing it by hand. But some tricky features may still need people to fix them.
Common Pitfalls
Migration can be hard. Problems often happen with data types. SQL Server and PostgreSQL use different types for boolean, arrays, and JSON. To stop mistakes, teams should do these steps:
Install the right PostgreSQL ODBC driver for their computer.
Use SQL Server Management Studio’s Export Data tool.
Pick SQL Server Native Client as the source.
Choose .Net Framework Data Provider for ODBC as the target.
Set up the ODBC connection string for PostgreSQL.
Check and change data type matches.
Fix type problems, like exporting SQL Server boolean columns as int4.
Teams should also look at ODBC settings. They should uncheck ‘Bools as Char’ to make sure data changes correctly.
Azure Database for PostgreSQL
Azure Database for PostgreSQL is a managed cloud service. It helps companies move from SQL Server. The platform has features to keep data safe and lower downtime. Companies can get up to 58% return on investment. This is because of cloud scaling and automation. Many customers save up to 60% compared to using their own servers. Azure Database for PostgreSQL lets you do both offline and online migrations. Offline migration is easy but needs downtime. Online migration keeps downtime low. It works well for big or important databases. The service can move any size database. It has both portal and command-line tools for more options.
SQL Server professionals can use what they know to learn more. They should look at how architecture, memory, and process management are different. They can try tuning queries and making indexes better. It is important to learn about handling transactions and ways to back up data. They should also check out high availability and disaster recovery choices. Setting up labs at home and using cloud services helps them practice.
Community forums, online classes, and expert blogs give helpful support for learning more.
FAQ
What makes PostgreSQL different from SQL Server?
PostgreSQL is free to use. It works with many data types, like arrays and JSON. It uses MVCC to let many people use it at once. SQL Server costs money and works best with Microsoft tools. Both can handle big data and hard questions.
What tools help migrate data from SQL Server to PostgreSQL?
Teams use tools like AWS Schema Conversion Tool and Database Migration Service. DBConvert is another tool. These tools move tables, data, and code. Some tools help fix problems with data types.
What is MVCC in PostgreSQL?
MVCC means Multi-Version Concurrency Control. It lets many people read and write at the same time. Readers do not stop writers. Writers do not stop readers. This keeps things fast and safe.
What backup options does PostgreSQL offer?
PostgreSQL can use pg_dump for logical backups. It can also use file copies for physical backups. You can do point-in-time recovery with WAL. Cloud services often have automatic backups.
What is Azure Database for PostgreSQL?
Azure Database for PostgreSQL is a cloud service. It takes care of backups, scaling, and security. Users can work on their apps. The service helps move data from SQL Server, both offline and online.