PostgreSQL

Deep dive into PostgreSQL fundamentals, performance optimization, and advanced database features.

Overview

This section covers core PostgreSQL concepts and advanced topics that help you build performant, scalable applications on SerenDB.

Topics Covered

Performance Optimization

Query Performance

Learn how to write efficient queries, analyze query plans, and optimize slow queries.

Key concepts:

  • Query planning and execution

  • Using EXPLAIN and EXPLAIN ANALYZE

  • Index usage and optimization

  • Join strategies

  • Query rewriting techniques

See: Query Performance

Index Types

PostgreSQL supports multiple index types, each optimized for different use cases:

  • B-tree: Default index type, good for most queries

  • Hash: Equality comparisons only

  • GiST: Generalized search trees (geometric data, full-text)

  • GIN: Generalized inverted indexes (JSONB, arrays, full-text)

  • BRIN: Block range indexes (large sequential tables)

  • SP-GiST: Space-partitioned GiST (non-balanced structures)

See: Index Types

PostgreSQL Version Management

Version Policy

Understand SerenDB's PostgreSQL version support policy and upgrade path.

See: Postgres Version Policy

Upgrades

Learn how to upgrade your PostgreSQL version safely with minimal downtime.

Best practices:

  • Test in branches before production

  • Review breaking changes

  • Update extensions compatibility

  • Verify application compatibility

See: Postgres Upgrade

SQL Reference

Query Reference

Comprehensive guide to PostgreSQL SQL syntax and commands:

  • SELECT statements and clauses

  • INSERT, UPDATE, DELETE operations

  • JOIN types and syntax

  • Subqueries and CTEs (Common Table Expressions)

  • Window functions

  • Aggregate queries

  • Transaction control

See: Query Reference

Key Concepts

ACID Properties

PostgreSQL ensures:

  • Atomicity: All-or-nothing transactions

  • Consistency: Database constraints maintained

  • Isolation: Concurrent transactions don't interfere

  • Durability: Committed data persists

Transactions

BEGIN;
-- Your queries here
COMMIT;  -- or ROLLBACK;

Constraints

  • PRIMARY KEY: Unique row identifier

  • FOREIGN KEY: Referential integrity

  • UNIQUE: No duplicate values

  • CHECK: Custom validation rules

  • NOT NULL: Required values

Views

Create reusable query abstractions:

  • Standard views

  • Materialized views (cached results)

  • Updatable views

Common Table Expressions (CTEs)

Write more readable complex queries:

WITH active_users AS (
  SELECT * FROM users WHERE last_login > now() - interval '30 days'
)
SELECT * FROM active_users WHERE plan = 'premium';

Performance Best Practices

Query Optimization

  1. Use EXPLAIN: Analyze query execution plans

  2. Add appropriate indexes: Speed up frequently queried columns

  3. **Avoid SELECT ***: Request only needed columns

  4. Use LIMIT: For pagination and testing

  5. Optimize JOINs: Ensure join columns are indexed

Index Strategy

  1. Index foreign keys: Improves join performance

  2. Compound indexes: For multi-column queries

  3. Partial indexes: Index subset of rows

  4. Don't over-index: Each index has maintenance cost

  5. Monitor index usage: Remove unused indexes

Connection Management

  1. Use connection pooling: Reduce connection overhead

  2. Limit connection count: Based on your compute size

  3. Close idle connections: Free up resources

  4. Use prepared statements: Reduce planning overhead

Data Modeling

  1. Normalize for consistency: Reduce data redundancy

  2. Denormalize for reads: When query performance critical

  3. Use appropriate types: Smallest sufficient data type

  4. Partition large tables: For time-series or multi-tenant data

Advanced Features

Full-Text Search

Built-in capabilities for text searching:

  • tsvector and tsquery types

  • Multiple language support

  • Ranking and relevance

  • GIN indexes for performance

JSON/JSONB Operations

Flexible schema with SQL querying:

  • Path expressions

  • Containment operators

  • Index support on JSONB

  • Schema flexibility

Array Operations

Multi-value columns without JOIN tables:

  • Array constructors

  • Element access

  • Array operators

  • GIN indexing

Range Types

Efficiently represent intervals:

  • Date ranges

  • Numeric ranges

  • Custom range types

  • Overlap and containment queries

Troubleshooting

Slow Queries

  1. Check execution plan with EXPLAIN

  2. Look for sequential scans on large tables

  3. Verify index usage

  4. Check for implicit type conversions

  5. Review JOIN order and strategy

Lock Contention

  1. Keep transactions short

  2. Acquire locks in consistent order

  3. Use appropriate isolation levels

  4. Monitor lock wait times

Storage Issues

  1. Monitor table bloat

  2. Regular VACUUM operations (automatic in SerenDB)

  3. Use pg_repack for severe bloat

  4. Partition large tables

Learning Path

  1. Start here: PostgreSQL Introduction

  2. Performance: Query Performance

  3. Indexes: Index Types

  4. Reference: Query Reference

  5. Advanced: Explore functions and extensions

Resources

  • PostgreSQL official documentation

  • SerenDB-specific optimizations

  • Query optimization guides

  • Performance monitoring tools

Master these PostgreSQL fundamentals to build robust, high-performance applications on SerenDB.

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