PostgreSQL 17 New Features - Performance and Usability Improvements

PostgreSQL 17 Overview

PostgreSQL 17 is a major release featuring SQL/JSON standard compliance for JSONB, incremental backup, and significant performance improvements.

SQL/JSON Standard Support

JSON_TABLE

Handle JSON data as relational tables.

SELECT *
FROM JSON_TABLE(
  '[{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]',
  '$[*]'
  COLUMNS (
    id INT PATH '$.id',
    name TEXT PATH '$.name'
  )
) AS users;

-- Result:
-- id | name
-- ---+------
--  1 | Alice
--  2 | Bob

JSON_QUERY / JSON_VALUE

-- JSON_VALUE: Get scalar value
SELECT JSON_VALUE(data, '$.user.name') as name
FROM events;

-- JSON_QUERY: Get JSON value (array/object)
SELECT JSON_QUERY(data, '$.user.tags' WITH WRAPPER) as tags
FROM events;

JSON_EXISTS

-- Check if JSON matching condition exists
SELECT *
FROM products
WHERE JSON_EXISTS(attributes, '$.colors[*] ? (@ == "red")');

Incremental Backup

Back up only changes since the last backup.

# Take full backup
pg_basebackup -D /backup/base --checkpoint=fast

# Take incremental backup
pg_basebackup -D /backup/incr1 \
  --incremental=/backup/base/backup_manifest

# Merge during restore
pg_combinebackup /backup/base /backup/incr1 -o /restore

Benefits

Performance Improvements

VACUUM Speedup

PostgreSQL 16 vs 17:
- Large table VACUUM: Up to 20x faster
- Memory usage: Up to 20x reduction

I/O Optimization

-- New I/O statistics
SELECT * FROM pg_stat_io;

-- Results include I/O statistics per backend type

Index Improvements

-- BRIN (Block Range Index) improvements
CREATE INDEX ON events USING BRIN (created_at)
WITH (pages_per_range = 32);

-- More efficient multi-column BRIN

New Features

MERGE Statement Extensions

MERGE INTO inventory t
USING new_items s
ON t.product_id = s.product_id
WHEN MATCHED THEN
  UPDATE SET quantity = t.quantity + s.quantity
WHEN NOT MATCHED THEN
  INSERT (product_id, quantity)
  VALUES (s.product_id, s.quantity)
RETURNING *;  -- Added in PostgreSQL 17

Partial Aggregate Pushdown

-- Faster aggregation on partitioned tables
SELECT date_trunc('month', created_at), COUNT(*)
FROM events  -- Partitioned table
GROUP BY 1;

New System Views

-- Progress of running queries
SELECT * FROM pg_stat_progress_copy;
SELECT * FROM pg_stat_progress_basebackup;

Logical Replication Improvements

Failover Slots

-- Sync replication slots on standby server
ALTER SUBSCRIPTION my_sub
SET (failover = true);

Conflict Resolution on Subscriber

-- Configure behavior on conflict
ALTER SUBSCRIPTION my_sub
SET (disable_on_error = false);

Migration Tips

# Pre-upgrade check
pg_upgrade --check

# Upgrade with pg_upgrade
pg_upgrade \
  -b /usr/lib/postgresql/16/bin \
  -B /usr/lib/postgresql/17/bin \
  -d /var/lib/postgresql/16/main \
  -D /var/lib/postgresql/17/main

Summary

PostgreSQL 17 makes enterprise use even easier with SQL/JSON standard compliance, incremental backup, and significant performance improvements. Applications handling JSON data will particularly benefit from the new JSON functions.