PostgreSQL 16: New Features Every Developer Should Know

PostgreSQL 16, released in September 2023, represents a significant step forward for this powerful open-source database system. With improvements spanning performance optimization, developer experience, and advanced capabilities, this version brings several noteworthy enhancements that can dramatically impact how developers build and maintain data-intensive applications.

Performance Enhancements

Parallel Query Improvements

PostgreSQL 16 takes parallel processing to new heights with significant improvements to its query parallelization framework. These changes have particular impact for analytical workloads:

• Parallel VACUUM: Finally, maintenance operations can leverage multiple CPU cores, dramatically reducing downtime during routine table maintenance.
• Enhanced parallel sequential scans: Better distribution of work among worker processes improves scanning performance on large tables.
• Parallel bitmap heap scans: Index-based operations now benefit from parallelism, accelerating complex queries with multiple index conditions.

Logical Replication Enhancements

Logical replication gets major upgrades in PostgreSQL 16:

• Two-phase commit support: Ensures atomicity across distributed transactions in replicated environments.
• Binary transfer of large objects: Reduces network overhead when replicating tables with large binary data.
• Conflict resolution improvements: Better handling of conflicts when multiple sources modify the same data.

sql-- Configure a publication with improved conflict handling
CREATE PUBLICATION app_publication FOR TABLE users, orders
  WITH (publish_via_partition_root = true, conflict_resolution = 'apply_remote');

Developer Experience Improvements

JSON/JSONB Enhancements

JSON handling sees significant improvements in PostgreSQL 16:

• New IS DISTINCT FROM operators: More precise JSON object comparison.
• Performance optimizations: Faster processing of large JSON documents.
• Enhanced JSON path querying: More powerful filtering expressions.

sql-- New JSON query capabilities
SELECT * FROM products 
WHERE product_data @? '$.attributes[*] ? (@.color == "blue" && @.size > 10)';

SQL Language Enhancements

SQL syntax expansions make queries more expressive and concise:

• Improved MERGE command: More complete implementation of the SQL standard MERGE operation.
• New regular expression functions: Including regexp_count() and regexp_instr().
• Enhanced DISTINCT ON capabilities: More flexible ways to eliminate duplicates.

sql-- Using improved MERGE for upsert operations
MERGE INTO customers c
USING staged_customers s
ON c.customer_id = s.customer_id
WHEN MATCHED THEN
  UPDATE SET name = s.name, updated_at = now()
WHEN NOT MATCHED THEN
  INSERT (customer_id, name, created_at) 
  VALUES (s.customer_id, s.name, now());

Security Enhancements

Security sees meaningful improvements in PostgreSQL 16:

• SCRAM channel binding: Stronger authentication with support for channel binding to TLS connections.
• Enhanced role management: Better methods for tracking and limiting role permissions.
• Improved SSL/TLS support: Expanded certificate validation options.

sql-- Configure stronger authentication requirements
ALTER SYSTEM SET password_encryption = 'scram-sha-256';
ALTER SYSTEM SET scram_channel_binding = 'require';

Advanced Features

Pluggable Table Storage Interface

One of the most forward-looking features in PostgreSQL 16 is the pluggable storage interface, opening the door to custom table storage implementations:

• Custom table access methods: Develop specialized storage formats optimized for particular use cases.
• Alternative storage architectures: Enable columnar storage or other formats without forking the core PostgreSQL code.

This foundation paves the way for specialized optimizations similar to what’s seen in the PostgreSQL ecosystem extensions like TimescaleDB and Citus, but with deeper integration into the core system.

Incremental Sort Enhancements

The incremental sort feature introduced in PostgreSQL 13 gets significant improvements:

• Extended incremental sort support: Works with more complex query patterns.
• Better performance for presorted data: Optimizes cases where data already has partial ordering.

sql-- Query that benefits from incremental sort optimization
SELECT * FROM orders
ORDER BY customer_id, order_date DESC
LIMIT 100;

Query Syntax Extensions

PostgreSQL 16 expands SQL capabilities with new expressions and syntax:

• Range type containment improvements: Better handling of range data types.
• New aggregate functions: Including array_agg enhancements.
• Improvements to CTEs (Common Table Expressions): Better optimization of recursive queries.

sql-- Using enhanced CTE features
WITH RECURSIVE hierarchy(id, name, path, depth) AS (
  SELECT id, name, ARRAY[name], 1
  FROM departments
  WHERE parent_id IS NULL
  
  UNION ALL
  
  SELECT d.id, d.name, h.path || d.name, h.depth + 1
  FROM hierarchy h
  JOIN departments d ON d.parent_id = h.id
  WHERE h.depth < 10  -- Depth limiting for safety
)
SELECT * FROM hierarchy ORDER BY path;

Administration and Monitoring

Database administrators benefit from several key improvements:

• Enhanced pg_stat views: More detailed performance statistics.
• Improved EXPLAIN output: Better query plan visualization.
• WAL compression: Reduces storage and I/O needs for write-ahead logs.

sql-- Example of improved EXPLAIN visualization
EXPLAIN (ANALYZE, BUFFERS, FORMAT JSON)
SELECT count(*) FROM orders 
WHERE order_date > current_date - interval '30 days';

Migration Considerations

When upgrading to PostgreSQL 16, consider these important points:

1. Review deprecated features: Some legacy functions and behaviors are marked for removal.
2. Test query performance: Query planner changes might alter execution plans for complex queries.
3. Evaluate security implications: Some default settings provide stronger security but might require application adjustments.

Use the pg_upgrade utility for in-place upgrades:

bashpg_upgrade \
  --old-datadir=/var/lib/postgresql/15/main \
  --new-datadir=/var/lib/postgresql/16/main \
  --old-bindir=/usr/lib/postgresql/15/bin \
  --new-bindir=/usr/lib/postgresql/16/bin

Conclusion

PostgreSQL 16 delivers meaningful improvements across performance, security, and developer experience. The introduction of the pluggable storage interface is particularly forward-looking, creating new possibilities for specialized storage implementations.

For developers, the enhancements to JSON handling, SQL syntax, and parallel query processing offer immediate benefits for both new and existing applications. These improvements continue PostgreSQL’s tradition of bringing advanced database features to an open-source platform while maintaining the reliability and stability that organizations depend on.

Whether you’re building a new application or maintaining existing PostgreSQL deployments, version 16 provides compelling reasons to upgrade and take advantage of these new capabilities.